Weather in mid May is lovely. Summer-like (but not oppresively hot) without the daily afternoon storms, so days at a water park, or an afternoon swim, are fun. The nights aren't a lot cooler, so shorts and tees are fine all the time. The crowds aren't too bad, as mentioned above.
When my daughter was little, I would go every year.
We also had a "change of life" baby (my son), so I would sometimes get the grandma remarks. The fact that my husband's hair started turning grey at 21, and was almost completely white by 40, didn't help much. (Unfortunately, both of my children have that gene) We don't get them as much now since my son is 16 and taller than both of us.
Don't let the avatar fool you - it's 7 years old! :lol: