Oooo, I love roadtrips!
I agree with what everyone has said so far. My route would be thus:
North to Niagra Falls, via Vermont, with a short stop along Lake Champlain. I’d take a trip up to Montreal for a day, if you have time.
Next, southwest via 90 and then 80. Spend the night in LaPorte, Indiana, if you can. There’s a cheap little B&B there on the lake that is simply heaven.
Then, on to Chicago. You simply must see Chicago. Have dinner. Take in a musical. Visit the lake. Whatever.
Even though it’s boring, I’d continue on 80 through Des Moines, Omaha and Lincoln and would avoid going south to St. Louis to catch the 70. The traffic is bad in St. Louis, people don’t know how to drive on the freeways there, and the Arch is a huge let-down. Instead, catch the 76 to the 70 and drop down into Denver. There’s absolutely TONS to do in Denver. If you want to get the kids good and tired, Water World is big fun. There are terrific museums, theaters, shopping and dining. If you just want to get out of the city, try Garden of the Gods in Colorado Springs, or visit the little town of Steamboat Springs, where olympic athletes come to train. There’s terrific trout fisihing at Steamboat Lake, where you can rent a little cabin and take a boat out of the day. You can stop in Palisade and visit the Rocky Mountain Meadery for a few samples of locally made mead. Yummers.
But don’t waste any time in Grand Junction. There isn’t much to see there. Instead go south down US Hwy 550–The Million Dollar Highway–for some of the most beautiful country you will ever see. Stop and stay in Durango for at least a day. Great fishing, hiking, kayaking, biking and golfing are available to travelers. Then head west to Mesa Verde National Park, and don’t forget to check out the local museum there. Holy moly, is it ever cool. If you have time, drive north on Hwy 666 to Hovenweep National Monument. It’s worth a look.
There’s plenty to see in Utah, too. Try to hit Bryce Canyon National Park and definitely don’t miss Zion National Park. Yeah, it’s $15 to get in, but it’s the most beautiful of all the national parks I’ve seen.
Then south to Vegas, of course. If you’re feeling adventurous, there’s a skydiving company in Boulder City you should visit.
From Vegas, just head straight for the ocean. Then south to L.A., Orange County and San Diego. You could spend a month there just playing.
Have fun!