Octane's for my husband with 3 extra shots, and I vary between the strawberry, mango or a combo. We have a collection of their mugs because it seems every trip to Vegas we make we always forget our mugs (cheap refills when you have a mug already)... but the reason we hit his specific one up, rather than the other locations is the staff. They all have great people working there, but these guys go a little above :) (and one of the guys is from CO too)
You can't go wrong with a giant slushy that gets you a good buzz after one drink... and besides when it is 115 out a cool mug (that stays cold cuz of the insulation around the mug) goes down very nicely