Yes, I went to a McDonald's while in Vegas. I even went twice *gasp*
The first time was because my friend and I felt that we had lost enough at the blackjack table, so we went to McD's to drown our sorrows in some milkshakes and McFlurries while practicing with a deck of card and some nickels.
The second time was because we hadn't eaten lunch, but we knew we wouldn't be able to make it until dinner :) So we stopped really quickly for some fries...and more McFlurries ;)
The service isn't the quickest, but they are friendly and the food is good! Stop in for a quick treat!