First, you're coming to Las Vegas.  What happens here, stays here.  Sin City.  whatever.

I'll first direct you to a fairly decent article in the July 2007 issue of Playboy that revolves around Nikki Avalon (probably one of the best and well reviewed indies in town).  There's some paragraphs there that outline what you can expect when coming to Vegas and not doing any planning in advance.

So, you decide to come to Vegas without making arrangements with one of the well reviewed ladies in the review section.  What to do?

Well, brothels are good but they are a bit outta the way.  and you specifically states lounges, bars, and clubs.

In many casinos, esp the more expensive ones, you'll find bar girls looking for a random hook-up and waiting for their cell phone to ring (they usually double as agency girls and try and get to the room quickly).  One major point is that bar and agency girls don't care about customer service like a good, well reviewed indie does.  Their service tends to be mediocre to poor to outright ROBs (ripoff bitches) or worse.  Still, for some, it's the game of the hunt/chase to find that diamond in the rough, the rare one that turns out to be GFE (or better).  This town is not built on winners and playing this game, you tend to come out losing more often than winning.

As for other "pros", there are dancers in strip clubs that might be willing to see you outside the club (extras inside the club tend to be extremely rare).  For someone in town a short period of time, it usually takes a lot of cash to get one of these lovely to your room and the experience can be less than satisfactory.  

The final option is to look for ladies in the various nightclubs, concert venues, and ultralounges.  These types of places generally charge cover.  You can find a large variety of places from casual, playing hip-hop or house/techno or latino rhythms or country/western or punk or blues/jazz or some kind of performance (comedy and magic and cirque du soleil and showgirls tend to be common).  It helps if you can dance and have no qualms about coming up to random members of the opposite sex and maybe finding a one-night stand.  Some of the more popular clubs tend to have limited seating available, making bottle service a key to getting the real estate to allow your potential hook-up to rest their feet (and snag a drink).

Personally, you should pick up a VIP membership here ($20/month), get access to the reviews, better search options, and find a provider that can find the time to see you while you're here.  If you two meet, you're sure to have a good time and probably one of the best value for your entertainment dollars.

Bob