Who should I take on my road trip?

I am planning a 2000mile road trip that would cover 5 states. At first I planned on going with friend A on the beginning of Aug and after that I plan on going to Yosemite with him. I just found out that I I had to postpone the trip for a week.Friends A Yosemite trip is on the following week and my dilemma is that I am planning the road trip for 2 weeks. Friend B could go on the second week and in addition stay for the whole 2 weeks. Both friends are really close to me and they have helped me through alot of difficult times and I feel Im in their debt. I feel really bad now that I have to pick one or the other and I know its their 1st opportunity they have to get out of CA