We have visited the first week of April the past several years and this year will be there 3/30-4/6. Sometimes Easter falls in there, like this year.
We have a ball!!!
The weather is perfect - sunny, warm but not hot. We almost never have rain.
Use the heck out of fastpass. We literally get another FP the moment the next one is available. My husband and I act as FP runners. While the other does something with the kids (snack, bathrooms, show, shops, etc) the other runs and grabs the FP. We use the WDW wait times app to decide which one to get next.
Dining - all sit down reservations are made. For counter service try to go early or late. We are fine eating lunch at 11 so we try to do that to avoid crowds.
Arrive at the parks early! Cannot stress this enough. You will get so much done between opening and 11 you will set the pace for the entire day. My kids are older (11 and 15) so we try to hit parks early at least half the trip. The other days we sleep in, revisit a park, do downtown Disney, pool, etc.
Drive your own car. We used to always take the busses. Many trips we waited forever, were packed like sardines, froze from the A/C, had to balance sleeping kids and strollers, etc. At some point a couple years ago we tried driving our own car. A world of difference! We all have a seat, ride in comfort, have room for our stuff, parking is free cause we are on site, and if you arrive early you get a parking space so close you don't need the tram.