its late but i figured i would post what i figured out too in case anyone is doing searches for info.
I bought a nashbar bike bag, I don't really like nashbar stuff but couldn't turn down the $50 price tag. it doesn't give any padding but my bike made it both ways with the only problem being a bent skewer for the front wheel which in hindsight i should have taken out when packing. it was alright to carry a short distance with the shoulder strap but more than a 1/4 mile becomes a real pain. what helped a lot was having a backpack arkel pannier and putting most of my other stuff with the bike, so i only had the bike bag, 1 pannier to carry and the backpack. this was for a light tour in SE Asia, if i was doing fully loaded with camping gear i still don't know how i would be able to carry everything. also second having a bungee handy is always a good idea for stuffing the bag in the trunk - although the bag also fits in the backseat of most cars pretty easy.