We have gone the last 6 years in June. Once DD started Jr high and they frowned on us taking her out for a week in September. We actually went the last few days of May thru the first week of June, by the time we left it got increasing more crowded but still less that later on in June. I didn't mind the heat at all. July was HOT June was good, but a lot of rain which worked out well because a lot of people didn't come out and we had less crowds to deal with. Looking forward to going again in September. We usually stay at Coronodo Springs and I think it was 30% off the room rate but we always add on the tickets and dining to make it a package.