the 17mm (for drain plugs) x 27mm (for rear axle, triple nut and swingarm nuts) would be cool to have for touring, altho a bit expensive:
http://www.bikebandit.com/msr-rider-wrench?WT.mc_id=2194329
http://www.bikebandit.com/msr-rider-wrench?WT.mc_id=2194329