Google "Lolo's Extreme Cross Country RV Trips". It will give you some valuable info re: long trips and routes/times and what works and what doesn't.
One thing about having a TC, it's perfect for long hauls cross country. Get up early and drive. Take quick breaks during the day. Make your long break at dinner time. Enjoy a nice meal, stretch, and drive until midnight. Pull off and grab some sleep until 6-7 am and hit the road again. Interstates are the only way to go when just covering miles.... plus you can always find a rest stop for the night. My DH and I trade off driving and can cover a lot of miles this way, but we enjoy driving and consider it part of the adventure :)
I'd do a marathon if I wanted to get to a family reunion and was staying in one place. We have found that 12-14 hours is about our daily max. You end up eating either fast food or snacking while driving. And 3 days would be the max we'd do this for before stopping.
