I'm not sure if Spring Break has started yet or not, but I will say that I tried to get a hotel room ( a few weeks ago) for this Thurs & Friday and there was NOTHING available. On site Disney hotels were completely booked, both the Sheratons were completely booked, HOJO was full, etc! We finally ended up at Candlewood suites a few blocks away by the I-5. I think it's a fairly new suite hotel.
Anyway, by the absence of vacancies at the local hotels, I'm saying it will be crowded.