Birch ply is a popular option these days. It's not always easy to find, or as cheap as plywood, but can be finished a lot prettier and is lighter. Lowe's, if you have Lowe's, carries 3/4 in 4x8' sheets for a good price, and it makes great cabinet material. If you have access to a lumber yard I highly recommend 1/4 " birch ply. It will cost the same as the 3/4 but is much better for walls and ceilings. Any 1/4 wood paneling works well though if you are covering it.