They are all over the place in Vegas: one by the door at The Cromwell (Flamingo side), one in the very back of Bellagio (had never made it that far back before), one near Hash House at Linq and two in Aria near the hotel lobby. The big hits really come from the bonus round and you really need to hit all five symbols to get a decent pay. That being said, I took over $700 out of the ones at Aria betting $2.50 and had some terrific group play at Cromwell netting a nice $75 bucks for each of the five players.

Edit: Crap, forgot about the money hungry ones at Planet Hollywood. Three of them near the new burger joint and the front door next to Pink's.