Avoid wood underlays where possible. The cheap tables found in department stores often carry these inferior products. Hardwoods are lovely for cuesticks but are subject to humidity and can crack or warp as a pool table component, destroying the level of the table.
I also prefer three-piece slate construction with slate liners supporting the weight. The giant slab of slate on a one-piece slate will sag due to its own weight but a multipiece slab with will play beautifully for decades. Careful when lifting three-piece slates so they will not form bad spots along the seams where they are joined.
Check carefully at installation time, when the dissembled table in put together on site. Any cracked, warped or badly dented slate should be returned for a replacement from the table manufacturer.
