I always start planning my days based on EE. Do we want to get up early and go? If yes, then the park is decided. If not, then avoid the park having EE. It will be more crowded.
I have heard to avoid the MK on Sat., Sun., and Mondays. Logic here is locals on the weekends and people arrive over the weekend and start their trip at the MK.
We plan around the fireworks at the MK too and other things we want to see. For instance, when we will be there in Jan., Spectomagic is only on Fri. and Sat. No Sat. at the MK for us, so that puts the MK in the Friday slot.
Another thing to consider is transportation. Once you have moved to the Dolphin, you may want to take the boat or walk to Epcot and MGM instead of using your car. You could do those parks on Dolphin days.
You could go ahead and make your PSs at the 90 day mark for the most important places you wish to eat. Once the park hours are out, you can make others. Hours are usually released 60 days ahead. For example, Jan. hours were issued Friday.
Should be warm enough for water parks with out a doubt. We were there in mid March one year and got almost cooked to death at a Braves spring training game!