K.S.
Always an issue with taking an Easter vacation from Michigan is the weather, as you know. Driving to get to a warmer climate is going to be a 15 hour drive. Staying close to home will be a cold vacation, likely.
Last year we flew to Charleston after a no flying vacation break from before our DD was born. It was lovely. Shorts weather, walking on the beach and getting the toes wet, but cool nights.
We've driven to the Smoky Mountains. Avoid Gatlinberg; go to Pigeon Forge instead. It could still snow in April, though. You can camp or get a cabin or hotel room. Or go to the caves in Kentucky.
Go to Chicago on the train. It is amazingly inexpensive. Just be sure to return a day early in case you are forced to bus it home instead. While in town, take buses to all the points of interest. Very kid-friendly town. Get a hotel with a pool to have a low-key day.
We've also driven to Virginia, which is also a 15-hour jaunt. There's a lot of history there, so there is something for everyone. Monticello; Blue Ridge Mountains; Civil War sites; Revolutionary War sites; presidential homes; spring flowers; the ocean, if you go far enough.
West Virginia is closer and beautiful. We went white water rafting there on the way back from Virginia, but it is worth the visit itself. There are cabins you can rent in the state parks.
If you need to get away and don't want to spend a lot of time in the car or money, you could go to Toledo for a few days. Get a hotel near the Cosi science center (I think it is the Windemere). One day Cosi; one day the zoo; one day the art museum.
Or Ann Arbor :)! One day the Natural History Museum (dinosaurs); one day U-M art museum and archeology building (Ancient Egyptian pieces); one day the Hands-on museum; another day the Botanical Garden (indoor garden--very warm and relaxing); Leslie science Center (birds of prey to view--all incapable of living on own in nature--beautiful animals);
Greenfield Village will have an exhibit on the Titanic that begins in
March or April. It's the 100th anniversary of the sinking.
Have fun with whatever you decide to do.