Hi UrbanSherpa,
There is a conveniently located REI in Henderson just 5 or 10 minutes from the Las Vegas airport, right on your way to the Grand Canyon. Check REI's website for directions.
Since this is my first post, I'll go ahead and say hello to everyone. I've been lurking here off and on for a year and just got around to registering yesterday. I'm heading out to the Whitney area from Ohio in early August, to do some dayhikes from Horseshoe Meadows and then do an overnighter on the MR. I really enjoy everyone's trip reports and pics here! Lots of valuable information too!
Cheers,
Pete