I was looking at the Mirage, Monte Carlo, and Mandalay Bay for good pool areas, but will any of them be open in early March? If so, will it be warm enough to enjoy them?

They will be open. It is up in the air whether or not you'll be able to enjoy them. I've been in Vegas in March when it was warm enough to swim, but I know it can also be chilly that time of year. I wouldn't count on it as your only source of entertainment, but that shouldn't be a problem in Vegas!

The average high in Las Vegas during March is in the 70's but peaks at only 75. Not exactly hot but that depends on where you spent the winter!

I don't believe that the Mirage pool is heated. It can be cool even in July, in my whimpy opinion!

daph, are you serious? I'm from Phoenix and most people I know don't get in pools in July because they're like bath water. Vegas pools can't be much different.