New rules to ensure post quality. See this thread for details.
I actually did a very similar drive a couple of months back. I'll second the 70-68-79-70-465-74-80 routing. But it's actually slightly shorter to jump off I-80 near Iowa City and follow I-380/SR 27/Avenue of the Saints up to Clear Lake and take I-35 north to I-90 west. But the difference is maybe 10 miles?Enjoy the trip. There's a lot to see and do along the route, especially in South Dakota.