Keep in mind that Easter is very early in 2008 - like March 23 or something. Spring Breaks will likely be over by your week. There are no park hours listed for April yet, which is sometimes an indication of the crowds they expect. The parks are staying open late, til 10:00, from March 15 - March 29, then they go back to closing at 7:00 or 8:00. It looks like those are the weeks they are expecting to be busiest.
Also, there are on-site hotel specials for April 13 - June 4, which is another indicator that they may be expecting spring break crowds to be gone. There are no supersaver rates for this time, yet, but they are advertising Extra Value Weeks right now, and the above referenced time frame is included in the promo.
If you just can't swing staying onsite, be certain to get to the parks very early in the AM. You may not need express passes or fotl if you go early, especially if you have several days to visit the parks. Check the hotel you are staying at to see if they offer free shuttle service and what time the shuttle begins running. You may be able to save yourself the parking fee as well.
We are a very large family - 6 children, but only 3 left at home. There would be no way we could stay onsite if we were traveling with all our kids. Last time we vacationed in Orlando, we had all our kids and stayed at the Holiday Inn SunSpree Resort in 2 connecting rooms. Our kids loved it.