I'm very happy with the Corbin Dual Tour that we installed. Passenger position is waaay better than stock, offers major improvements. Rider position is maybe 1/2" or so closer, and definitely lower, and has a flatter seating area so you can move around a bit to find your comfort zone. Both positions have a receptacle for Corbin's removable backrest.
Because of the shape of the passenger section, it definitely changes the look a bit, but it's definitely worth it for the long distance comfort. It also uses the stock mounts and lock, so you can pop it off and put your stock seat on in a couple of seconds.
more info here
http://raiderperformance.com/ourbike.htm