Having spent a fair amount of time in all of those places, I would definitely recommend the West Coast option. Maine, NH and Vermont will not be that different from Maryland. The general trees, plants, coastline, and scenery will all be very similar. The west coast is very different. The entire lifestyle and culture will seem subtly different, in a good and interesting way. It will also be rewarding simply driving across the country, seeing such radically different landscapes. If you go the Maine, NH and Vermont route this will not be the case.
Unfortunately the cost of gas is becoming very prohibitive, but with a few friends things should be manageable. On your west coast trip, Yellowstone is worth a look, as are Crater Lake, the rainforest, and some of the larger mountains. Why not climb a real mountain while you're out there? Rent crampons, boots, and a mountaineering axe. Learn how to self-arrest, then go climb Mt. Olympus or one of the other volcanoes. Definitely visit the coast.