Your brother's place really is probably the nicest, cleanest place in Moab. The only big problem with staying there is if you want to have some jeepin' friends come to hang out with ya. No one but paid guests were allowed in when our friends stayed there. Security gates and a guy on a golf cart kept a very tight perimeter. We wanted to grill dinner and hang out with them one night, but weren't allowed to.
Hopefully that's one of the rules that changed.
I'll second what Tom said. We've always enjoyed our stays at the KOA and always use their cabins. They recently built several new private bath rooms that are great and the hosts are very helpful and friendly.