There is a big difference packing between solo and 2-up. Solo, I put no clothing in the bags, just gear, tools/parts, half cover, water, rain suit, tire plugs/pump, waterproof gloves, a fleece warmup, one towel. All my motel stuff clothes/tennies/toiletries goes outboard in waterproof bag tied on back. As soon as you arrive, no fooling with bags, just grab your travel bag off the back, and take it in the room. It doesn't come out until the trip is over. Half cover used nightly stays in the shower, but everything in the bags, stays in the bags (and that is all stuff I might need while riding every day). Only thing that goes in and out with me is the pistola.
The tall kitchen bags are great for wet gear after the rain on the road, dirty clothes, muddy shoes/boots, and general segregation of clean and crummy or wet and dry, and cram to any shape you need. I keep a kitchen bag in the room and roll my sweaty/dirty clothes in it as the week progresses (no locker room smell this way).
Here's my solo travel motel bag for up to a week or more (contents stay dry even at bottom of pool) (this works great on the supervalk, but on the trunked interstate it is too big for the back seat unless end to end, but then you can't get the trunk open without moving it; I won't put anything that heavy/large on the trunk rack):
http://www.twistedthrottle.com/dryspectm-d38-rigid-waterproof-motorcycle-dry-bag-in-black-grey-or-orange I suppose with 2-up, even packing as much as you can outside, she gets one bag too. I'd try to get one of those tall backpack sissy bar bags and get clothing for two in that (if possible).
A good goal is motel stuff carried outboard, bike/ride/fix/travel/rain stuff in the bags.... as much as possible. This cuts down on having to get stuff in and out of the bags daily.
If you pack those liner bags to full capacity, you probably cannot get them into or out of the bags. Packed light enough to get in and out, you are wasting bag space or have to cram stuff down around the edges (and then they still won't pull out).
And no shopping for anything bigger than a bikini on trips.
