Don't feel bad about hand planing the boards.
My local sawyer (thankfully I found him on the second try) looked at me like I was nuts when I told him I wanted to hand plane hickory to size for a bench. His comment was along the lines of "Not afraid of hard work, huh? Make sure and eat your Wheaties before you attempt it." He was right. . .hand planing a bench of hickory is not easy, but it is an indescribable satisfaction to be able to do what most people are either not skilled enough to do or don't have the patience/endurance to do.
That being said, I'm not sure I would go back to that sawyer, Rob. I can handle a lot, but poor customer service is not something I handle well.
Also, I would take Mr. Posey's advice. Unless you're up for crazy clamping and some cussing, having something to build a bench on is a great idea. I'm trying to build a laminated hickory workbench right now, and after 2 months I finally have the base done (and finished with a coat of BLO). It was not easy, and the tiny bench my wife bought from IKEA didn't last through the mortises I chopped out. So like David said, make sure and make a solid base, mate it with a slab (but make sure it's removable from the base), then work on laminating something. Double bonus, you can use the slab for another project, or maybe even some sort of table.
The Barefoot Woodworker.
Fueled by leather, chrome, and thunder.