Amie,
There is always something exciting going on at Walt Disney World!
During your visit the most notable one that I can think of is the Epcot
International Flower and Garden Festival. Now that may not sound of interest to a pair of 2-year old boys, but even they will find some neat things to discover, like the character-shaped topiaries.
While I don't see this event pushing as large of a crowd as the Food and Wine festival, you will be there during the start of the event, so expect some decent sized crowds at Epcot from those looking to see the event kickoff.
Generally however, you are there at a moderate crowd level time, before most Spring Breaks bring the larger groups into the parks, so you should be really enjoying their visit!
Please feel free to write me back if you have any follow-up questions!
Have a magical vacation!