If you're just comparing the beginning of June to the end of June, I definitely think beginning of June is better! This is when my family has always gone (typically the last few days in May through the first few days in June). My husband is a school administrator and we always leave the first day we can after school gets out. The way we've always thought about it is that the further you get into June, the hotter it gets, and the more crowded it gets (as more and more schools are letting out for summer). For us it's always been the perfect balance of being able to go when school is out, but it's still not TOO hot (compared to later in the summer), TOO crowded (compared to spring break or later in the summer), or TOO expensive (like thanksgiving or Christmas break). Hope this helps!