I thought FSD would be great on a long trip... Nope, that's not really what it's meant for, it's meant for secondary roads and cities. Regular AP is better on the highway.
FSD kept putting me in the second lane from the right which really annoyed other drivers because while the speed limit was 65 or 70 and I was doing 75-78 (range/ speed compromise), many others were going faster and it would try to move over to their lane all the time. It's like the default. I can see them gaining on me way back in the rear view mirror, but the cars like "I don't want to be in the right lane, people merge here", and it would just move over and people would eventually zoom up on me.
Didn't matter if I had "minimize lane change" on or off, it didn't drive with consideration for faster drivers on the road. I kept having to manually cancel lane changes that I ended up just using regular AP.