Now for a real adventure rent 650's take hwy 15 to Primm NV turn right into the mountains (see google earth) at the big 2 star casino ($35 a night). There you will find the trail head to 1000s of miles of desert riding.....did a couple single day trips in there on the xr650r dualsport and had a blast, stayed in Vegas most nights.
No worries though your ride is going to be a hoot as planned. Check out some, of the back roads in DV, many are easily done on the GS without knobbies. If your interested in that check out the group ride thread called Death Valley March Madness Rally. Although this absolutely incredible rally is already fully booked this year I'm sure you will find some links to GPS tracks that work well for the bigger bikes. There is one ride that I remember was maybe two hours off the maim hwy and you went one way through a steep canyon (minivans Suv's also). Plus there were a few old mines.....
There are a few of these side trips that make the DV experience much better. The rally is at Panamint springs Resort in DV which has camping and a few rooms. Being from the north staying overnight in the desert is quite a treat.
XR650R dualsport/Rally Trainer
“We should come home from adventures, and perils, and discoveries every day with new experience and character”