There are some amazing places to Latin dance in this city, and if you're willing to travel off the strip a little you'll definitely find the real deal.  


Gold Coast - club Noches Calientes on Saturdays.  This is a big place, I think they have two rooms, definitely a Latin crowd.  It's one of those Latin places you see in the movies that gets sweaty and more impressive as the night goes on.  Excellent place to hang out and have a drink and even just watch.  They have some incredible dancers that come out to this one.

Las Palmas Mexican Restaurant - Thursdays.  This is inside the Commercial Center (you know where the green door is, etc) They have a massive floor area that turns into a full on dance class on Thursdays. Sooooo fun!!!  Definitely worth checking out.  Real deal here also. More of a family place, the lights go down, the dj comes out, and all ages are on the dance floor.  The food is great too.

Havana Grill - Friday and Saturday  (this is pretty far off the strip, but if you're staying at Green Valley Ranch then it's perfect)  This is a Cuban place and you won't find a much more authentic place to dance to Latin music.  They have a great restaurant bar so if you just want to hang out you will find it a cool place to do so.  

Rhumbar at Mirage - I personally haven't been but it seems to get good reviews.  


Many of the nightclubs feature Latin nights and it's not commercialized.  There is a pretty substantial Latin community in the Vegas area and they love to dress up and go out, when the nightclub features Latin/meringue/salsa they bring in a well know dj and go all out.  You wont get a bunch of drunk white people stumbling over their feet and dancing to the macarena.    

Found a couple of calendar for you to check out...
http://lvsalseros.com/salsa-clubs/
http://www.salsapower.com/cities/us/lasvegas.htm

Have Fun!!