You can fake this pretty effectively in Altium Designer.
Altium has what they term "Recyclable Schematics" - Schematic layouts that you can paste into larger schematics and treat as components.
Duplicating the PCB end is a bit more work, but definitely doable (I've done it). Basically, you route the DC-DC on one board, and then simply copy-and-paste the design into whatever new board you have. This will move the component footprints, and traces, but not the nets. Then, assuming you have the corresponding schematic entity, the next time you synchronize the schematic and PCB, Altium will match the free-floating footprints to their schematic entities, and add the netlabels to the existing copper.
Alternatively, assuming you are OK with not being able to edit the DC-DC layout in situ (on the PCB), you can just paste the layout into a footprint library, and define where you want input and outputs to be.
In this case, you would edit the library file, and then propagate the changes out with the "Update from PCB libraries". You can also modify the primitives of a component once it has been placed, but changes there will not propagate back to other places you have the component.
Third, Altium can embed one board into another - I use it for panelizing things, but I think you could probably also use it for embedding one functional section into another. It wouldn't tie into the schematic, though.
It's worth noting that I do the first two of these regularly at my job (usually with FTDI USB-Interface circuitry) - It's definitely a viable approach.
I recommend Noise Reduction Techniques in Electronic Systems by Ott for such topics.
Don't have seperate grounds, but do only connect them in one place.
Connect the ground to the plane; don't route ground (or power)
Best Answer
No, not really. What you are asking for is called auto-placement, which largely doesn't exist, and works poorly when it does. This is one of those problems where the human brain is still better than software. Determining layout is a complex issue with a very large solution space, and as such hasn't yet yielded to anything more than toy software implementations.
However, most of the rest of going from a schematic to a PC board can be automated or at least largely assisted by commonly available software. Even for layout where the human makes the decisions, the software can make sure some basic rules are met.
Once you have a layout, which defines where what parts go on the board, then the next step is routing. That refers to figuring out where all those copper tracks go that form the connections between the parts. For this step, auto-router software is available and can be useful. Even that isn't to the point where you can fire and forget, but such software can take care of a lot of the details for you.
Usually routing is a iterative process between you manually adjusting a few things, then letting the software do the grunt job of routing the things that are less critical. Sometimes the software can't find a solution, or you don't like what it did. You then move a few things around, manually route some traces, set some constraints, and let the software try again.
Anything that calls itself a E-CAD (Electrical Computer Aided Design) package will have schematic capture and routing capability. Some will additionally have auto-routing capabilitiy or at least the option to add it. Examples of such E-CAD software are Eagle, Altium, and quite a few others.