Going over Spring Break (Easter) is peak season. The only real discounts you'll find are
AAA as previously mentioned, and the discounts at the Swan and Dolphin if you qualify for a nurses/gov't./teacher's discount. There may be a few other discounts here or there, but nothing really substantial. Who knows, maybe Disney will cut us all some slack and offer up some discount codes, but I'm not betting on it!
I was shocked at just how crowded it was during our April 2001 trip. Yes, the weather is beautiful, but it is standing room only! You really need to take advantage of the Extra Magic Hour (formerly called Early Entry) and Fass Pass. I remember during that April trip getting a Fast Pass for Test Track. No kidding, we waited in a line for 15 minutes just to get the Fast Passes!
I said we'd never go again during that time of year...but you know the old adage;
never say never! We just may be returning during Easter break in 2004!

It's gotten to the point that we really can't pull our boys out of school anymore because it's just too hard for them to catch back up when we return.
So, it's either during spring break, winter break, or the heat of the summer months.