I have three possibilities for the inset black areas...
1. 3/8" black granite tiles, weight about 2.3 lbs./sq.ft
2. 1/2" soapstone tiles, weight about 9.2 lbs./sq.ft.
3. 1/2" ply plus laminate or 1/2" mel board, weight about 2 lbs./sq.ft. for the mel, less for ply
Each possible choice presents problems. My preference would be for the soapstone - even though it is much more costly - because it isn't much more difficult to work than wood which means I could easily get a flush surface between it and the wood surround. The problem is the weight...using it, each table would weigh 150 pounds or more. Not real easy to move to clean around.
The problem with the granite or mel/laminate is in getting it and the surrounding surface flush. Can't sand so that means plane/scrape/router trim, all of which are possible, just a bit of a PITA. There will be a shimming underlay under the tile so I'd be able to get it pretty close so the leveling of the wood surround would be minimal. Still, I'd really prefer the soapstone; maybe I'll do it and just forget about moving them to clean :)
I'd really appreciate comments/suggestions from y'all.