Looking for a tougher 75 mile option from Vermillion? Here is a great down and back route to Laurel, NE. This route has a nice five mile warm-up and then once you see the bridge to Nebraska, the fun begins.
There are a few initial rolls to Hwy 12 in Nebraska and then just one hill by Maskell and then it's flat to Obert. Once you hit Obert, the rolling hills are pretty much there until Laurel, save for a couple short flat sections.
The main thing to remember, to make sure you don't miss a turn on this trek, is to watch for the Hwy 15/Laurel sign off Hwy 12 once you get by Obert. The Hwy 15/Laurel turn is about 1/2 way down a hill and is at a funky angle. So, if you hit Wynot, NE, turn around, you went about three miles too far.
Enjoy the hills! It's a good workout and the area is pretty scenic.