We take our Suzuki Burgman 650 with us in an enclosed cargo trailer.  We ride 2-up.  This summer we will be riding the San Juan Skyway and all over Yellowstone!!  We can't wait!!  
The Burgman is a large scooter weighing over 650lbs with full tanks.  It gets only 50mpg or so with 2-up riding at 50-55mph, so not the greatest on fuel.  Speed up to 115mph (but never us!!).  We have been riding one since 2005, and we currently own a 2012 model.
Suzuki also makes a smaller Burgman 400 which I highly recommend.