The three most important things to me are:

1 - One table firmly attached to a wall (with the legless design) for attaching a vise to - one mistake I made originally with mine was I made it too wide, I thought a nice wide table would give me lots of room, but it made it difficult to reach the items on the peg board behind it!

2 - A second, free-standing table (Preferably on wheels) so that you have 360 degree access to whatever you're working on.

3 - Lot's of good lighting!