Welcome to the RTA Forum!

You've got a few areas where your drives are not feasible or at least not ideal.

First, under no circumstances should you consider driving from Chicago to Denver in a single day. At 1000 miles, that's 2 full days on the road. Trying it in one is both dangerous and will have you in no condition to do the rest of your drive.

Kansas City is an ok distance for a stopover, but it really is out of the way. It would be quite a bit shorter to take I-80 through Nebraska. Along the same lines, if you really want to get to Vegas in 3 days, then Denver isn't really a good stop either. Denver to Vegas is 750 miles, which is also too much for a single day. If you want to get to Vegas in 3 days, you should look at stopping at Grand Island, NE and Glenwood Springs or Rifle CO. Those are going to be 10+ hour days, which won't leave you time for doing much other than covering miles.

Trying to get from LA to San Jose via the Coast Highway is a very long day (likely 14 hours or so), and following it up by trying to get to Portland the next day - another 12 hours. Neither of those drives would really be recommended, and doing them back to back isn't a very good idea.

Your drive back is pushing things as well, and you really don't have much time to stop anywhere there either, including Mt. Rushmore.

Doing everything you want in 3 weeks isn't impossible, but it would be a pretty quick trip. How much time do you want to spend in Portland and LA? Have you considered flying out west and then driving? That would make it a lot easier to fit everything in, and give you time to fit in the other sites and kitschy things you are interested in.