Heavy wood table top support design
I have two black walnut slabs 20"W x 96"L x 2"t and then I want to put another piece of wood between them to get a roughly 4 foot wide table. I will be gluing them all together but being a big table top i want to make sure its supported really well.
First question would be what tone wood should I put in the middle, really dark, really light, or try to match the black walnut tone?
Secondly I have two train of thoughts for supports. Either make a couple dado cuts about 3/4" deep width wise and nail in a hardwood board OR just make a 2x4 support system underneath the top. If I was going with the 2x4 route I would make them out of 1x4 oak boards and glue together for nice straight supports?
I'm really new to big woodworking so any help would be much needed? Thank you.