Found a place that rents some nice adventure bikes in CO: http://www.houseofmotorrad.com/our_motorcycles.html
I may go and rent a 800GS from them for a day to see how it feels. Been pondering a F8000GS or a Tiger 800XC for a new bike next year. They seem to be something that can take some abuse and still be planted on the road. The Tiger is the preferred bike, but no one rents those as they are in such high demand right now.