I'm planning a massive road trip across North America for this summer. Reddit, what places do I need to include?

First off, I live in Tennessee. I've seen quite a bit of the Southeast already, so ideally I'd like to focus my attention on sights that aren't here. (But I'm definitely willing to bend that rule if there are some cool things to be seen.)

The tentative plan is to work my way up to Vancouver, travel down the Pacific Coast to San Diego, and the head back home through Arizona, New Mexico, & Texas. I'm also open to venturing down through Mexico a bit as well.

I'd also love to head up to the Northeast (especially Maine & Montreal) at some point, if possible.

I'm really just looking for ideas here, so if you know of a certain town or attraction that would be a great place to visit, please share. Thanks!