I can't speak to American pricing, but if there is a HP ProCurve Switch in your price range then you might want to take a look. I've found their products to be keenly priced (in the UK anyway), great performers, and very well supported products with a very good guarantee.
I'm not personally a fan of DLink in general but can't comment on the specific model you are looking at. Regardless of what model you buy in the end you have the right idea with going from a group of 'home' products to a business class switch, but also consider the environment - clean power, well ventilated, decent cabling will all help...
Your proposed setup looks fine to me, I think you'll certainly see an improvement in reliability and throughput by reducing the quantity of switches and improving their quality. Simple is nearly always better.
You do have to consider that any product, no matter how well built, how well recommended, how well cared for can fail occasionally. If an outage is unacceptable, then whatever product you buy then it might be worth trying to find the money for two in case of a problem. Whether or not the risk vs. investment makes sense for you is something only you can decide.
I can say that from running a major business network, just about every make of 'business class' switch I've used has been very reliable - as long as they're not dead on arrival they should last for a very long time. The ProCurve switches have had the best record in this area for me, which is why I like to suggest them to others.
I'm going to invoke Occam's Razor on this. While I suppose it's possible that some specific malformed packet(s) could cause your lower cost switches to fall into the failure mode you're describing I'd consider that a very unlikely cause. The switches that you're describing as having problems (small, unmanaged switches) aren't likely to have spanning tree implementations, let alone support for layer 3 switching and dynamic routing protocols. That type of switch should be "blind" to the actual content of the frames its switching, beyond using the source and destination MAC addresses to make switching decisions.
This makes me believe that you had a power issue more widely than you realize.
Going with a power issue assumption, I'd say you're having problems with the low cost switches because they're likely low quality switches. I know this sounds trite, but that's been my experience with networking gear over my entire career (with very few exceptions). You generally get what you pay for (and, though something may be priced incorrectly the market sorts that out pretty quickly).
A higher cost switch is typically going to have a better power supply that is more likely to run within tolerances when exposed to "glitchy" utility power. I suspect that the power supplies in your lower cost switches probably started putting out bad power when the utility power went out of spec. At that point, some part of the "brains" of the switch ended up in a "this should never happen" scenario because one or more of the power rails drifted too far out of tolerance.
An Ethernet switch isn't typically a single ASIC running the whole show but rather are typically groups of systems of ASICs that do different jobs connected to each other. Without knowing about the architecture of the switch in question it's hard to say anything definite. I've had experiences with a model of switch, many years ago, that used a single ASIC to run a group of 4 ports. Certain types of failures would cause groups of 4 ports on the switch to "flake out" while the rest of the switch kept running fine. A partial failure of a switch isn't abnormal in my experience.
In the case of your failure, the parts of the switch that handled keeping the lights on, for example, kept running fine. The physical interface hardware (the PHYs) probably kept running just fine (since you were probably seeing "lights" out on the far ends of the connections). Something else, however, didn't keep working right and you ended up seeing a lack of connectivity. In the cases where I've been "fortunate" enough to catch a switch "in the act" of failing like this I've plugged my laptop into a "problem" port and observed (using Wireshark) a totally "dark" network without any broadcast packets or the other "noise" commonly associated with a typical "working network". Packets transmitted into these ports never showed up elsewhere in the network-- they just fell into a "black hole". I bet you'd see something similar in your situation.
Best Answer
Grounding for safety (vs grounding for signal integrity, which is a whole different issue, see below) is primarily a concern for equipment in a metal enclosure. If there is a wiring fault inside the device (frayed wire shorting against the metal inside), then the outer shell of the unit may be electrified. Guess what happens when you touch it? Ouch! By having a ground path, you give the electrical current somewhere else to go (instead of through your body when you touch the device).
You will notice that most devices in a metal enclosure will have a 3-prong input power (if the power plugs in directly without an AC/DC power brick), and also a chassis ground screw.
If you are grounded through the power cord, the middle prong should be connected to the building's wiring and then to an earth grounding rod, assuming your building was properly wired using modern building codes. There are inexpensive testers that can check to make sure your outlet is wired correctly.
If you use the chassis ground screw, you typically connect it to a grounding bus bar mounted on the wall, which is then connected to an earth ground. If you don't have a bus bar in your setup, you might be able to "cheat" by wiring it up to the grounding prong or center screw of an electrical outlet. (This is not ideal, and probably would not pass a code inspection, but it is better than nothing.)
Your local safety codes may require one or the other be hooked up, or both. It may also depend on whether it is a temporary item (e.g. a 5-port switch on someone's desk), or a permanent installation (something bolted to a wall). Check your local codes.
For rackmount devices, they are typically grounded to the metal frame of the rack by being bolted to it. Then there is is typically a grounding connection from the metal frame of the rack to a bus bar, which in turn grounds all of the devices mounted in the rack. This is in addition to the grounding provided via the power cords. Cable conduits, ladders, rack doors should be grounded as well (any exposed metal). Page 3 of this PDF provides a useful illustration.
For a consumer-grade desktop switch in a plastic shell like the ones you mentioned: There is usually no option for attaching a ground because it is not required since there is no exposed metal. The only things you should do is make sure your outlets are wired correctly (using the aforementioned tester), and use a surge suppressor (power strip or UPS).
Grounding for Signal Integrity: The other reason you might need to pay attention to grounding is if you have a signal integrity problem (corrupt data). Two big ways this can come into play:
In an electronic system, ground is the reference point for "zero volts". Ground is not the same everywhere you are, so two physically separate systems may disagree on what is a "1" or a "0". This can lead to all kinds of "interesting" communication problems. A common way you can run into this is if one of the computers connected to the switch is on a separate electrical power system (e.g. two buildings connected by an underground cable). In that case, it is recommended that you use fiber ethernet (not a consumer grade switch).
Electronic interference and "noise". Power cables running next to data cables. EMI due to a large electric compressor next to your wiring closet. These kinds of problems can be mitigated with grounded conduits and other forms of shielding (or just use fiber).
Generally speaking, Ethernet is is much more forgiving than say RS-232 when it comes to grounding issues because the signaling is differential and uses an isolation transformer. So, you usually do not need to worry about signal integrity grounding in a typical office environment. However, problems can still occur in "harsh" environments, like a factory floor. If you have a higher-end managed switch, it can give you statistics on Layer 1-2 communication errors, which will give you some idea if there are physical problems with your wiring that need to be addressed.