I'd give Adonia a call over at TLC.  She's got a lot of young, lean stars on her roster and a lot of them enjoy greek.  There's also an agency that specializes in LV girls but I'm blanking on their name (100proof, maybe?).  There's also Pamela Peak's agency that also has lots of girls in Vegas... and I think HelpUBookHer has a few there too.  

You should also head over to the porn star ad board - there are several stars advertising tours in Vegas and one might be to your liking and be in Vegas during the days you want.

My suggestion for someone you might like: Lauren Phillips - she's sometimes in Vegas - she's young and thin and fun. I'm pretty sure she's scheduled to be in Vegas in January but I'm not sure of the dates (probably near to AVN).

If you choose to go with a gorgeous mature woman with skills. Read my review of her - best night of my life. I plan to repeat often.

I am here in Vegas available for Greek.
Very hott, young, lean
Hit me up! I can do in call and out call