i'm not sure of the spring break dates for the parks yet for 09.
go to the calendar at the uo site. see what hours they have. if they are extended, you can assume they expect larger crowds on those dates.
also, if you check the prices for the epp, it is another indicator of estimated crowd levels for your dates.
the higher the epp, the more crowds.
if you see the cost to be $20, low crowds.
that is how i estimate crowd level in the future.
i stay on site and get to use the fotl but i still go when i can avoid large crowds.
just because my wait in line for a ride or attraction is short, i still have to deal with lines for the restrooms, food purchase and walking shoulder to shoulder in the park. so, i try to hit "better" crowd days for us.