I think President's week is doable. Easter week is always insane, and next week Easter is on April 16 which I am sure is going to coincide with a whole lot more Spring breaks than usual, so I am sure it is going to be jam packed, every park every day. Because of when it falls, I told DH that there is no way we can go that week. I just don't feel it will be enjoyable.
This year our Spring break is not for another two weeks, so I am hoping the crowds are bearable, but I can't imagine going next year at Easter. We have been there several times for President's week and with PS's in hand it's not a problem. Like luvmarypoppins, we have been there several times when restaurants would not take walk-ins and I'm not talking the obvious ones. We were at Mama Melrose, Chefs de France, etc. and they simply stated to everyone that walked up, "Sorry no walk-ins." We felt so bad for everyone. We thought it would have beeen helpful if they had posted signs outside because while we were waiting to be seated (and we had to wait even with a PS) group after group would come in, wait to get to the podium and then be told there was nothing. So, if you go either of those times, you must have PS's.
Obviously the weather is warmer Easter week, so you can use your resort pool more, but last year at the Boardwalk, it was sometimes hard to find chairs. They went around checking ID's and asking people to leave.
What's the most crowded time you've ever gone? We've been there President's week, Easter week, Spring break week, and Christmas week. Christmas week was by far the worst but Easter was a close second. It really depends upon how much you need to see and do while you are there. Between the DVC and the AP, we now have a whole different attitude when we go. What we don't get to on this trip, we'll get to on the next. But, even with that in mind, I can't bring myself to go next year during Easter, and I love, love, love Disney! It kills me to give it up, but people couldn't even get on site this year, there was NO availability whatsoever, so you know it was crazy, and many schools did not even have off the week of March 27,(we didn't) so I just can't put myself through that. Especially since I feel that next year everyone will be off at the same time. I may be wrong, but I am not going to take that chance.
Good luck with your decision. If you do decide to go at that time, just make sure you have all of your plans in place, and build in a lot of relaxation time. Remember, there's no such thing as a bad time to be at Disney.