There's no site that talks about crowd levels, but I can give you some pointers.
The parks are obviously more crowded on the weekends.
The best time to go on any day is early.
The parking garage opens at 8am, be there when it does.
Get to the gate first and be near the front.
If the park stays open until 10pm, they expect huge crowds.
The time you are going is after spring break and before summer, crowds will be moderate.
From noon to 4pm is when the parks are most crowded and it's hot. That's when you want to leave, go back to your room, rest, and return for the evening.
