I think it's better to look for out-of-town MILFs on the strip vs looking further away where there may be more of a locals mix.  Your luck is better with the loose women here on holiday (and may drink more because they aren't driving) than locals that have their guard up.

That said, I'd lean towards bars and lounges in the evening.  Hotel pools during the day.  Avoid any nightclubs with lines.  The girls vacation in Vegas may choose a more value priced room to stay in so you might find better luck at low- to mid-tier properties on the strip.  Hanging out in the lounges next to a male stripper revue shortly after the show ends might find hot and bothered women that got rejected by the dancers.

Of course, if you're like most guys and don't make the aggressive move of approaching and chatting with any woman (or group of women), all you might find are bar girls.

Bob