My gf and I made the journey to Bentonville in June. It was awesome. It took 8 hours each way and we stayed a few miles from downtown. The Back 40 is, IMO, the crown jewel of that trail system. So great. I did much/most of Slaughter Pen and all of that was just a blast. We tried Coler, but the gf wasn't having it, so we bailed for SP. Also did Blowing Springs and a lot of the fun stuff near there, Sally, Wonderland, etc.
As much as I rode, I still didn't get to a lot of it. So, that means I/we have to go back...over and over until I have ridden it all. Then keep going because it's really something special. I would hate to be there for just two days. It really needs three, IMO. Two if that's all you can do, but take three or more if you can. It was great to be on trails that aren't solid chunder and chunk. A local we met described one trail we had just ridden (I think it was Black Apple Creek) as 'rocky.' After I did a double-take, we laughed...he has no idea what rocky means to a central Texas MTBer. It's all so fast, flowy and fun...just be prepared to climb...then enjoy all that sweet, sweet payoff. Can't wait to go back there. Planning something in the Fall (maybe) and the Spring (for sure).