What's the largest space that you think you might be able to have?

Mine's 6'x8', and I can do up to 16x20 pretty easily. I tend to print smaller, though.

The sink is the smaller version of The Sink. They're pretty convenient and have a good back splash. Dimensions given are internal, so it could handle two 16x20 trays. I used standard shelf ware next to the enlarger, so they go all the way up and down the wall. There are also shelves above the cabinet on the lower left.

If it helps, I've attached a floor plan. Another interesting configuration is to swap the door and the film drying cabinet.