The ideal world vs. what I'm willing to spend
I don't have a sleeve (yet). I bought a second-hand Crumpler "Very Busy Man" messenger bag and I just love it.
I do plan on getting a sleeve, though, for those days that I don't need to bring the kitchen sink along. If money were no object, I'd get the Waterfield Designs sleevecase with the shoulder strap and ballistic flap - that is the exact design I want (especially the flap, given that I live in the soggy Pacific Northwest). But yowsah! Who wants to spend $72 on a sleeve, for gosh sakes??
Anyone know of a sleeve that has a waterproof flap? I don't trust zippers to keep the rain out, and while Tom Bihn designs his excellent products up here he's located in the rain shadow of the Olympics (so he doesn't deal with Seattle rain, in other words).