i've gone in June (as this year for the convention), July and August---definitely pool weather. Since I stay at mid strip hotels (Wynns, Harrah's, etc) I don't have far to walk to go casino hopping and if I want to go to the south or north I get on the Monorail. I go to Fremont Street only if I want to eat at Hugo's Cellar and I cab there; I used to rent a car but haven't done so recently. However, there are some fun casinos and things to do out of the strip and so a car rental is a good idea.