The Walleye/Multi species style boat works great for Crappie fishing. I've run several brands/models from 17-21'. Crestliner/welded and Lund/riveted are my favorite two makes. They both have Crappie edition (triple seating) up front available.
Any boat will work but I want something that is roomy, stable, deep sides for safety/comfort and gives me a smooth ride in rough water.