We are about to plan a Universal trip & will stay on-site (don't know which hotel yet). It's myself, husband & 2 small children who will be about 3 yrs. & 7 mo. we don't want to go when it's too hot (85+) or when it's crowded. We can't go in Jan. & I'm thinking June is too hot so it's between Feb., March, April or May - which is the best month? i'm unfamiliar w/ how busy USO can get -although w/ Express will it really matter too much when we go? please help.