Will Neptune replies: I would get 8/4 maple or beech. Look for flat sawn stock with the rings parallel to the face. Rip it into pieces 31/4˝ or more. The idea is for the edges to become the bench top. The edges will be close to quarter sawn grain which will make the top more stable. Mill all the pieces and mark the correct planing direction of the edges which will become the top surface. Depending on your skill and inclination, you can skim the surfaces to be glued with a handplane or be sure to use a sharp set of knives in the jointer and planer.
Be very wary of snipe because all the snipes accumulate at the end, making it impossible to clamp the ends shut. It’s easier to get jointers to not snipe than planers, so one way out is to take one jointer pass on the planer-cut face to eliminate any snipe.
Then glue up sections. Make all the pieces have the same cutting direction. Glue up sections that will fit your jointer and planer. You can clamp top and bottom cauls along the length or the pieces to hold the pieces in alignment when you glue up.
When dry, you can now mill these sections flat and carefully join several sections together to get your final width, with minimal clean up. You can also take the finished piece to a shop and have it sanded clean and flat. Don’t forget to put the same finish on the top and bottom.