I owned a bike friday and rode it as my only bike for several years until it was stolen. I toured with it as well, riding it from Chiapis to Guatemala. I had a pocket rocket pro. While I enjoyed the bike tremendously, and the portability, I did have issues with poor shifting and frequent adjustments. I had a mechanic tell me its a problem on the smaller framed bikes with sti shifters, there is just not a lot of room between the rear hub and bottom bracket, and the lack of a top tube comprises stiffness. So, one solution is to use bar end shifters. With that being said, the ride was very comfortable, could easily ride 100 miles and my body felt no differently.

I have since replaced the stolen bike with a terry titanium isis as my go fast bike and a terry steel isis that I retrofitted with s/s couplers. My favorite of the 3 is the titanium isis, because it is the lightest and fastest. My second favorite is the steel isis, because it performs flawlessly, but it is heavier. My least favorite is the friday since it was also heavy and had performance issues.

Taking everything I now know, I'd try to get as light a full size bike as I could, ideally built with s/s couplers. The only downside to the s/s coupling, is that while it packs into an airline legal suitcase, it requires more technical expertise to reassemble/tune and doesn't quick fold to go on a bus or train, so it depends on your travel needs. I have friends very happy with their Ritchey Break a ways, anohter option, but they have longish top tubes so they don't work for a lot of shorter women.