I'd like to thank everyone, GeorgeC, Steve Neul, chopnhack, and BKBuilds for your helpful contributions. I've waited until now to respond so that I can do more research and factor in your help and let you know what i'm doing at one time.
First, I have a large new shop and want such a big work bench so that I can use it to work on more than one project at a time, using it with vices etc for wood work as well as assembly. Since it will be in the middle of the shop it is easy to walk around and close to everything else. The reason I think most benches are not wider than 30" is that they are next to a wall or not in the center of things. I fixed on hard maple because of its durability and that it be at least 2" for stability and wear.
I looked mightily for a prefabricated source, but as you couldn't fine any. I thought the problem would be the 48" depth, and that I would have to glue up 2 24" pieces, but the 8' proved a problem as well. There were some 8' long maple laminates but they were 30" or 36" deep, and I don't think any were thicker than 1 1/2". Baird Brothers Fine Hardwoods, www.bairdbrothers.com
, has 2" thick hard maple laminates but not in 48", but they will custom anything, and I'm having them make up what I need at a reasonable price, with a two week lead time.
I'm now on to wall storage. In addition to peg board I plan to 4" grid wire mesh on the shop wall to which various shelves, bins, baskets and clips can attach from Globalindustrial, and above it on the wall heavy shelving for wood storage.