Orlando is 1200 miles from Detroit, so that is a lot of range. My sister likes to drive from Flint to the Outer Banks at that time of year. My daughter prefers the Mississippi Gulf Coast in April, but keep in mind any warm beach locations will be drawing the college Spring Break crowds so facilities can be quite crowded and possibly noisy.
Much closer, Nashville can be nice in April, with much to see and do. However, it is at the latitude that can get heavy storms March through May.
Consider also Great Smoky Mountains NP (or Dollywood in the Smokies) which are one long day's drive from Lansing or Detroit.