I live in Denver. Calculated out that's only a cumulative average of 1.4% grade over 10.5 miles, but it's not a sustained climb and has some flat sections? Most of the actual "hills" on my ride to work are 4-6% when I calculate them out, which I was hoping were good tests. The one bummer is that I don't have the up and down rollers on the ride that you find in the midwest.
You can see the elevation profile at the link below. I was thinking that for cruising across Nebraska that heading up Lookout Mountain with my panniers might be overkill and not quite the same. I want rollers vs sustained climbing for the type of riding that will be.http://connect.garmin.com/activity/295157214
I planned on riding east out of Denver to Strasburg a few times for some overnight camping, and also down to Chatfield for some overnight camping. The road to Strasburg by Aurora Reservoir has some nice rollers. I rode that with a friend when he did his TransUSA trip.
Honestly, my biggest concern is that my typical rides to work and back are 10 or 12 miles each way. I'm only putting in 24 miles a day at present, 34 if I get crazy and take a different route. Sometimes I feel like I hit a wall right past the 25 mile mark as that's what my body is used to. I've done 150 in a day before, but that was a long time ago and my typical rides were 60 to 80 miles at a pop before doing it. I know the solution to that is to get my butt out there and ride.