Agree on the Speedway Motors museum!!! You will be blown away even if you don't like cars or history...lol.
Kawasaki plant may do tours, I did one in 1988 or so.
Eagle Raceway dirt track east of town at Eagle, NE.
I read somewhere not long ago that the tractor test museum tractors were getting auctioned off, maybe it was not all of them.
Can't go to Lincoln without a trip to Harbor Freight tools to get a whiff of China. I need to return my broken battery charger too....