Tim, the 1-1/2" laminated hardwood top came with the workbench, which I bought [link=http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200322005_200322005]here[/link]. I replaced the threaded casters with adjustable machine mounts.

When I get around to furnishing my workshop, I plan to make 1-1/2" benchtops by gluing 3/4" MDF on top of 3/4" plywood. The MDF makes a nice smooth worksurface, and the plywood will provide good load handing. Home Depot has this [link=http://homedepot.bighammersoftware.com/ProductInfo.aspx?cid=834245&pid=a46c77d2-f870-47e8-8fe0-0a1d1c1c4084]3/4" AraucoPly[/link] that I've found to be excellent material for benchtops. It's nearly the quality of hardwood ply but at regular pine plywood prices.

Solid Core door panels used to make great benchtops, but these days you need to be careful about buying them. Not all "solid cores" are made the same. There is lumber core, which is what they used to sell in the old days, with softwood (usually pine) sadwiched between hardwood (Luan, Birch, etc.) sheets. Then there is "fiber core", which has MDF for the core. There is even one with polyurethane foam filled energy-efficient "solid core" doors, which would be my choice for actually using as doors, but they make poor benchtops.