You might give some consideration to the Suzuki 650 V-strom. I've ridden but not owned one. At a claimed dry weight of 418 lb, it's 40 lb lighter than the 1000 V-strom and similar in weight to a BMW R100GS, which means it's a lot lighter than an oil head GS. At about $6650 msrp, it's a bargain, especially compared to BMW prices. The seat height is quite low for a dual sport so it might fit you well in that regard. I also found the stock seat quite comfortable, something I rarely do.

The 650 cc twin motor makes surprising power, providing considerably more acceleration than one of the 650 dual sport singles and I believe somewhat more than an air head BMW. It's also very smooth for a twin. After riding one, I would have no qualms about going two up on this bike despite it being only 650 cc. I found it to be a very comfortable bike. The after market is developing for this bike - Happy Trails now makes panniers and someone makes a robust skidplate (don't recall who), for example.

The down side would be lack of ground clearance and suspension travel, at least compared to a dual sport single, and perhaps fuel injection, which adds complexity. However, I'm not sure ground clearance and travel are deficient compared to a BMW, (I'm not familiar with current BMW specs). Never the less, this bike isn't ideal for heavy duty off pavement riding but it will handle unpaved roads that are at least somewhat maintained quite well.

I don't believe there is an ideal bike for a RTW trip, and taking a passenger certainly limits the selection somewhat. I have no experience with the Honda dual sport twins which aren't sold in the US - Africa Twin, Varadaro, Transalp. Perhaps one of these would be suitable for your purposes if you can find a low mileage one in good condition(occaisonally one turns up on ebay). I think a Bmw R80 or R100 GS would be a good choice (I've owned both), although R80 forks have been known to crack and I would start out with a new driveshaft in an R100 if doing a RTW.

Although a single, a BMW F650 GS (which I've also owned) can be used for two up travel as it makes more power than a typical single. Acceleration (one up) seemed quite comparable to the air head GS's I previously owned. The complexity of fuel injection in this bike might be a downside (although most fuel injection systems seem to be proving very relible). The chassis seems adequately strong for two up travel with luggage.

These are all just opinions, based on my experiences, about bikes I would consider if in your situation. Hope they are of some help. I'm considering a two up trip from Alaska to Argentina in 2006, and the 650 V-Strom currently heads my list of candidates for that trip. Of course, I may change my mind before then.

Mike

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Mike