I-80 straight across. good drive. I run this route several times a year.
Attempt to avoid Chicago between 6 - 9am and 3 - 7pm. I think there is one toll booth.
When you get to Sacramento, you may want to swing south on I-5 > I-205 > I-580 > I-680 .. This will help you avoid the east bay area.
You'll do a good long climb just east of Salk Lake City, and another just west of Reno (between Reno and Sacramento)
No big problems , just take your time. I have a driving tip that I pass on regarding mountain climbing:
Never go down a hill any faster than you were able to go up the hill.
I take my time, force the tranny into a lower gear so its not constantly shifting, fall in line with the 18 wheelers, turn the four ways on, and enjoy the ride. The same applies going down the hill, If I find I'm need to hit the brakes a lot to keep from building up speed, that means I need to slow down even more and get into a lower gear. The engine needs to be doing the majority of the braking.