My two cents....
Since I have hit a royal on almost every trip into Vegas (including during the convention... but we live an easy car ride into Vegas, so we go waaaay too much...), I have narrowed down my favorites to these...
Riviera: not great pay tables, but good drink service at the Splashbar (try to stay near Nick or Sonny the bartenders, tell them you're a chipper and they will take veeeeery good care of you). I have been lucky with several royals here.
Sahara: Pay tables are a tiny bit better, but the Thirsty Camel Bar (left of the Casbar lounge show area) is a friendly VP bar with great drink service, you can hear the live music from the CasBar lounge, plus they have a daily 4-of-a-kind card bonus there. Great place to sit late at night.
Main Street Station (downtown). Decent pay tables, nice microbrews and they have a 4-of-a-kind scratch ticket bonus. You must play 25 cent of higher machine and no deuces wild. I have been VERY lucky here and whenever you get 4OAK, hold up 4 fingers to the bartender, or hit your machine change light on and the floor staff will quickly bring you a scratchy ticket. I've never gotten over $5 (most tickets are $2 or $3), but it makes nice tip money. Very comfortable place to play...I've pulled all-nighters here and never ran into a "weirdo" yet...casino floor housekeeper even brought me a box of Kleenex one night when she noticed I had a cold (awwww, how nice!)
Boulder Station (off strip and my FAV!). Great pay tables! Nice clean casino with mega choices of machines to play and they have a good comp/cash back system. Food options here are excellent. If you have not eaten at the Broiler Room (steak house), you're missing out on one of the BEST steaks in Vegas with amazing prices (salad/soup bar here will dazzle you alone).
Have fun!

A royal at the Splashbar (note to self: turn OFF flash when taking picture..... )