Kitchen type base cabinets would work fine. I’ve been in a number of shops that recycled old kitchen cabinets from kitchen remodels and used them as shop cabinets. I’ve also set up 2 large maintenance shops using such cabinets; one plywood bases and one laminated particle board. Both used “formica” veneered kitchen counter tops. Both held up fine under the abuse of multiple, none to gentle, users, through neither stayed pretty for long.

4′ bases will be easier to make and install than 8′. When combined they will also be sturdier.

With the above said, I recently set up a third workshop in which I wanted the counter tops to function fully as secondary workbench tops. In this case I used simple 2 x 4
laminated H frame construction (3 1/2′ x 3″ legs with 1 1/2″ x 3 1/2″ cross members) to make a framework on which to attach a 3″ thick solid top (in this case made from solid core commercial doors). The H frames are attached directly to the wall studs. A ledger board is screwed into the wall to support the back of the counter top. The frames are spaced to accept free standing cabinets that can be slipped in between the framework. The cabinets themselves bear no load.

This has worked well and is serving as the prototype for counters that I am planing on installing in my home shop. The only major change will be to use laminated boards (or plywood, like Mr. Sellers current bench) instead of door slabs for the counter top..

Hope this helps.