Dave,
This is one of those religious discussions...
but fwiw, and imho, sure, the airhead G/S or GS is a fine bike to travel on.
For SOLO use, it's questionable though - I'd probably take an F650GS or a KLR650 depending on budget, or a KTM 640 Adventure for a lot of off-road.
The airhead beemers are great bikes, and can be very reliable if you know what you're doing, prep them right and maintain them right. The G/S is excellent solo, but definitely on the heavy end of the scale - great for primarily on-road, but loses badly to the singles off-road.
The GS is a great two-up bike, but I think too heavy for solo, especially compared to the competition.
(I'm actually more or less converting my G/S into a GS - but I'm 99% two-up)
But all the airheads are a victim of the late 60's technology that spawned them. Fantastically reliable then compared to what was available, but less so compared to what's available today.
It's a tough choice. One of the BIG things to take into consideration is your own PREFERENCES - if you LIKE a particular bike, and emotionally TRUST it, go with it over one that everyone ELSE says is a better bike but YOU don't like it.
Another biggie is your own mechanical abilities - the legendary "fix at the side of the road with chewing gum and string" capability of the airheads is useless if you don't know where to put the chewing gum. ride something intriniscally more reliable - and anything NEWish will be better.
All the non-airheads mentioned above, plus the Africa Twin, Transalp, DR650, and probably a few I've forgotten at the moment have proved themselves to be very capable and super reliable bikes. (Though the KLR needs significant tweaking, it's SO cheap that's forgiven)
Note that both the G/S and GS are available in the US, they are out there - you just have to be patient. first question to finally decide is two-up or solo.
ride what YOU like.
------------------
Grant Johnson
Seek, and ye shall find.
------------------------
One world, Two wheels.
www.HorizonsUnlimited.com