Now for a lid. I built the bench to fit a 15 inch deep lid - which would be built from two 1x8 oak boards biscuit joined together (7 1/2 inches wide each actually). This was a small scale practice run for when I have to reproduce the dining room window seat. Actually it's quite easy and after clamping for a day I had a pretty tight board which required just a little sanding to hide the joint. I then cut the lid to fit the opening and finally routered an edge bead to the entire front lip of the lid and ends to copy a detail from the window seat which is original to the house.
It's just mocked up for now. I need to run some cabling into the closet from under the stairs. Then I can add supports and line the inside of the bench to make a storage compartment. Finally I'll do the permanent install and add hinges to the lid. The design "feels" right so I think I got it close to what was originally there.