Originally Posted by drewguy

In August I would encourage a northern route. Grand Canyon and Arches (plus most other Utah parks) will be blisteringly hot. Instead from LA head up I-15 through Utah - perhaps drop through Zion - but then head up towards Tetons, Yellowstone and so forth - Maybe even Glacier NP. Also, if you're driving, consider the smaller parks that you may not get to for a full trip in the future - for example, Badlands. Mt. Rushmore/Black Hills in SD or Theodore Roosevelt in ND.

Agree with others that while there are things you can see once you get further east, it's less interesting.