Hifiman, your LT and the GL will run about neck and neck in the sportiness/handling department. The M/C magazine writers said the current 1800 (newer than '05 I think) are a tad better, but that's a subjective statement. I'd pick the GL but I AM a bit biased LOL. As for the ABS, I think you'd miss it. Goldwing binders are terrific, but the ABS is worth every penny to have. Be interesting to see where BMW goes with their flagship tourer once the LT is no longer; they are certainly trageted for the sport touring and sport market with their latest offerings of the 1300GT and the 1000RR.
Tralfaz, you can't actually compare a Springer, a GS and a Wing since they are three completely different types of bike. The springer gets it mileage out of less weight, and a torquey fairly large displacement v-twin. The heat you didn't feel on the Springer was because it is a unfaired cruise machine not a full Faired tourer. The Wings' fairing is a wind-tunnel tested piece of aerodynamics and is meant to isolate the rider and passenger from as much of the elments as possible. BTW, my '09 averages close to 50 mpg (Cdn) or about 42 US. That is comparable to a HD Ultra which weighs about the same, but the Ultra gives away a lot of agility and HP to the Wing. Would not even compare my old Roadking to a GL, again, too different.
Mike, there is as much difference in feel from the 1500 to the 1800 as there was from the 1200 to your 1500. Automotive comparison is like Cadillac Deville to STS to CTS4. Just keeps getting better.