Maldur,
I have experience here, I've been on 4-8 week road trip vacations across the U.S. on multiple occasions. In fact, I've driven in every state in the contiguous U.S. (never been to Alaska or Hawaii).
The best trip I've ever been on went like this...
Head South and West from Indianapolis to the coast.
Cross the Mississippi River at New Orleans, continue across to Texas.
Cut a bit north through Austin and San Antonio, across Texas to El Paso. Across New Mexico, through Santa Fe to Arizona.
From Arizona cut up across the Hoover Dam (stop for the tour of the dam) to Las Vegas. Spend 2 days in Las Vegas..
Then cut south into California to San Diego...see the San Diego Zoo
Head North then along the Coastal Highway (California highway 1) ...stopping at La Jolla Beach California
Also, a bit further north, stop at the Monterey Bay Aquarium.
Then cut a bit east and north in California and go through Yosemite National Park and Sequoia National Park to see the Giant Redwoods.
Continue up from their to Lake Tahoe and spend a day. From Lake Tahoe go North through Nevada to Utah...
Then North through Wyoming to Yellowstone National Park.
Across East from there to South Dakota and Mt Rushmoore (make sure you go through Wall, SD and stop at Wall Drug Store...heh, you'll get what I mean when you start seeing signs for Wall Drug when you're still 400 miles away).
East from there to Minnesota, stopping to see the Boundary Waters Canoe Area Wilderness...might want to plan when you'll be there and go to
www.bwcaw.org and book a permit to enter...you can book a permit for next year after February 1st. You'll need a guide and outfitter most likely...dunno if The Great Outdoors is your sorta thing though.
At any rate, just a bit further east and south through Wisconsin to Chicago where you spend the last full day and catch a flight out for home...
Lemme know if you have any questions...I've been to all of those places. It's a fantastic trip
Cedric - King of the Great American Roadtrip