My thoughts too. Have you thought of flying into any of the big cities out west, doing a loop trip and then flying back home. It would likely cut your costs. With your limited time that would probably allow you to see the most. It would be a shame to spend your time driving through areas which could easily be visited over a long weekend. Often return flights aren't a great deal more than a one way, and you would avoid the fee for dropping the car on the other side of the continent.

Buck's three steps in planning would still be relevant.

Lifey