Thanks for the reply

I'm not really fixed with the dates, I could probably go earlier (I'd prefer not earlier then 1. April)
Last time we did approx. 130 miles/day so I thought of about 6000 miles in total would be fine. I always thought a roundtrip is just too much and I would have to leave out multiple nice spots. A round trip would be about 11000 miles which means 137 miles/day (aleady subtracted the days I'll spend in SF and NY).

I think I will have to refine my must-sees to create a more detailed plan.