Ah, good question. I went with the Axiom rack, which you can get on Amazon for pretty cheap. I've used it a bunch since i first posed the question, and it's great. My only complaint is the way it mounts to the rear brakes - makes it kind of annoying to install and remove, but it's doable. I haven't weighed the load i usually carry, but I fill up my pannier set pretty tightly and it's still pretty solid. I highly recommend it.

I also recommend that Banjo Bros. pannier set. It doesn't come with a shoulder strap, but you can clip on a strap from a duffel bag easily enough. i bought mine from Calhoun Cycle: http://www.calhouncycle.com/