Google Maps – How to Change the Saved Zoom Level of a Map in ‘My Places’

You need to cluster your markers. It's tedious to do on the server side, but there are a few client-side clustering plugins you can use. The most popular one is MarkerClusterer.

MarkerClusterer v3:

• http://groups.google.com/group/google-maps-js-api-v3/browse_thread/thread/142dbdf66a94a133/71ec7c5c84cb6cd8
• http://googlegeodevelopers.blogspot.com/2009/04/markerclusterer-solution-to-too-many.html

Why many markers degrade performance, and how to improve it (MarkerClusterer comes out tops):

• http://www.svennerberg.com/2009/01/handling-large-amounts-of-markers-in-google-maps/

If you just need the image and don't need the underlying data, you can take a screen grab and print it out.

If you need all the data, you could download Google Earth, which I think still provides the offline functionality you're looking for. http://www.google.com/earth/download/ge/agree.html

To get everything on your device, you can make yourself a map with multiple destinations, then use the gear icon in the lower right corner of Maps to share the link to yourself. From there, you'll get a URL that you can send to your device.