"Two Up" Sport Tourer, eh?
Current or near future production, available in USA (Solo models excluded)
BMW - R1200RT ABS
BMW - K1200GT ABS
BMW - K1200LT ABS
Honda - ST1300 ABS
Honda - GL1800 Goldwing ABS
Kawasaki - Concours (No ABS)
Triumph - Sprint ABS (Chain Drive)
Yamaha - FJR1300 ABS
That's the only decent "two-up" sport tourers that come to mind at the moment. The Honda Goldwing and BMW K1200LT are both great two up tourers, but both a little light on sport. Off hand, I'd say the LT fits those with inseam greater than 30-32" better than the Goldwing.
I'd disqualify the Kawasaki Concours due to no ABS, and no fuel injection. I'd disqualify the Triumph Sprint due to the chain drive. Others my disagree.
That leaves the R1200RT, 2007 K1200GT, ST1300, and FJR1300.
The R1200RT probably has the greatest range (huge fuel tank, and great mileage), handles curves well, and should be very comfortable for two riders. Although very fast, acceleration will be the slowest of this group, especially when loaded two up with luggage.
The ST1300 has a great motor, plenty comfortable, but has been reported to be a bit unstable at speed, and many owners complain of excess heat on the rider.
The FJR1300 has been much modified (improved) this year, but remains a bit unknown. Did they solve the rapid camshaft wear problems? Did they solve the rider heat problem?
The 2007 K1200Gt is almost a total unknown. However, the engine is based upon the K1200S, which is terrific! The seating position seems to be adjustable from nearly the current RS to the RT, which should allow most riders to find a comfortable riding position. The smoothness and power should be VERY acceptable, as well as the handling two up.
I ride solo, not two up, (the wife rides her own R1200RT), and after much thought about the above listed models, chose the new K1200GT. My local dealer has my deposit, just waiting to place the order when BMW releases them. It will replace both my 2004 K1200GT and my 2003 Goldwing, although I'll probably hang onto the 'wing until I verify that the new GT actually fits me well enough to do thousand mile days. Although I love my current GT, it would take a lot of work before "I" could do much over a five hundred mile day on it. Yeah, I'm out of shape!
I'd really like a K1200S too, but the lack of decent nearby riding roads, AND my poor physical conditioning make that an unrealistic dream