Sounds like a great trip. I've travelled all over by motorcycle and here are my thoughts, for what they're worth:
1. Don't drive on the freeway. Yes its fast, but its boring. Take US highways or state highways. Better driving and you run in to the coolest people and things.
2. Get a National Parks Pass for $50 and visit all of the National Parks and other US Department of Interior sites that are along the way. The annual pass has a list of all of the parks, which also include things you've never heard of before (had you heard of the National Maritime Museum in San Francisco? Maybe, but there is a *ton* of stuff like that. Little Bighorn National Battlefield was one of the high points on a recent trip of mine). I promise you this is well worth while. You can even get a National Parks "Passport", which is a little book that has places for you to make a rubber stamp imprint at each park you visit. There are stamps at all of the visitor centers. The stamps have a date and it is cool to flip through it and see when you were there.
3. US50 is a great way east through northern CA if you *enjoy* driving. Drive around Lake Tahoe while you're at it -- but I'm sure you've done that. It might be too far north for you, but US12 through the Clearwater National Forest in Idaho is a religious experience. The best roads are road that go through National Forests. These often have a green dotted line next to them on the map. Always drive theses "scenic roads" when you have the option.
4. Bring a fork, knife and spoon, and keep them handy.
5. The coffee idea mentioned by someone else is a MUST. There is simply no good coffee outside of a major city.
6. Take pictures of everyone you meet, preferably with you in the picture. Ask them about cool roads and out of the way areas. A cool guy once told me about the "Lost Coast Road", which was another high point. I'm really bummed that I don't have his picture. Remember, you won't get to meet cool people if all you do is fly along "the Slab" (which is what motorcyclists call the freeway). Drive through lots of small towns. People on a freeway are eager to get somewhere. They are harried and tired and unfriendly. You want to travel the roads that nobody travels on and meet those folks.
7. "Eat Your Way Across the USA" is a cool book.
8. Keep a journal.
9. GPS is fun, but it can be a lot more fun to get lost.
10. You want to eat in small town cafes, especially in the midwest. You can get yourself a home-cooked breakfast any time of day that will keep you going all day long for about $4. Here is how you find them (you should be at least 10 miles away from the nearest freeway when you attempt this technique): Pull in to town and drive around until you find the cafe with all the pickups parked in front of it. That's where the locals eat. You should eat there too.
11. You need to drink lots of water (that probably doesn't apply so much if you're in a car).
12. If you haven't done it yet, drive through Death Valley on the way back (a National Park, again).
13. Don't drive at night and don't drive tired. Don't drive at night because you don't get to see anything. Seeing the country is supposed to be what its all about! Don't drive tired because it is dangerous and everything you're looking for is already right there. There just isn't any need to hurry!
14. If you take my advice and drive on the squggily blue roads (the secondary roads that are blue on the maps), you are going to need a good map. Rand McNally has a good set of 3 maps: Eastern USA, Central USA, Western USA. They save you a lot of money if you just get those three. You probably don't need maps for each state. If you take the freeways you probably won't ever need a map. Just look at the map posted near the restroom at gas stations to see your next interchange.
There is so much to see! I feel stupid giving specific ideas on where to stop. My best advice is to stay off the freeways (did I mention that???
) as soon as you are 3 hours from home and to not make any reservations or time commitments.
Make some BBS posts along the way so we can hear about your adventures!
Have a great trip!
Jim