Nelson Rigg Sportbike bags CL-890 ($104 at Amazon)
Here are the bags I mentioned a week ago, they hold about 9-10 liters per side, and are expandable to almost double that size. (expanded may not be good if you lane split)
I think they're well made, easy to put on, no frame required.
They have inserts to keep them in proper shape if not fully loaded.
Didn't include rain covers, but do on the larger model (CL-950) I'd probably just give them a coat of scotch guard, and put my clothes in plastic bags inside.
They have a neoprene pad to avoid scratching the bike.
The backs have additional clips built in to attach a top seat bag.
going to the Texas hill country this weekend, supposed to be a pretty great ride, will let you all know how the bags work out.
Matt