If cost is not the issue then try to remember the feeling you got at each school during the interview. Choose the one that you see yourself being happiest at. Both are pretty cheap as far as living and both are excellent schools. Also, all else being equal, another thing to consider would be the weather at both schools. They are definitely two extremes. That probably won't be your deciding factor but it's something to consider if there is one climate you really can't handle.
Ps I was accepted at UNLV and wait listed at Marquette. I absolutely loved both schools and could see myself at either one. I really hope I get accepted to Marquette. I would love to have the tough decision you have.