zxcvbob wrote:

Best thing I have found for the top is a used solid interior door.

I think the first order of business is to determine what the bench will
be used for...

For instance, a door or replaceable MDF top might make a good assembly
bench or machine table.

If you're going to flatten faces of boards with a hand plane, flatter
than the thicknesser leaves it, you're going to need a surface than can
be trued up on occasion with hand planes or cleaned with a cabinet scraper.

A surface used for lots of hand work is usually better without a
slippery film finish. On the other hand, the right film finish will
protect against glue, sharpening oils and water, etc...

I have surfaces ranging from melamine to urethane coated MDF to
unfinished pine and ash, depending on the use.

Lots and lots of very nice old benches have pine or fir tops that still
survive today. The surface doesn't have to be a hardwood.