A big enough work space to build a big ass table! My work table is 4'x8'. Made of 3/4" ply, covered with 3/16" tempered glass and retained by some 1" wide x 1/4" thick furring strips. I can work on 2 airplanes side by side. But, by having a huge ass table like that, it catches more of a damn mess than anything!
I like to listen to the radio while I'm working on airplanes. Lots of folks have flat screen TV's and cable or dish for service. My basement is always a dust factory, so none of that I would want in my TV or cable box. But I have a couple of old home stereo systems, so if they go kaput, it isn't a huge deal.
Drill press, scroll saw, band saw, sometimes an inverted router (for those without a laser in their shop), matching set of tools that copy what you carry in your flight box, screwdrivers, wrenches, allen wrenches, good cordless drill with 1/2" chuck and bits to 1/2", loctite, various glues, dremel moto tool, covering iron, heat gun, assorted screws (american and metric). The list goes on.
Basically, if you can think of it, it probably would be beneficial.