In fact, I'd take all Interstates - I-35 to I-135 to I-70 to I-25 to I-90. That's only 2260 miles, overnights in Hays KS, Casper WY, and Butte MT if weather cooperates. The E-470 toll bypass of Denver is cashless, license plate tolling, they mail you a bill ($13.25). If it's not rush hour, you can use I-270 (free) instead. The I-35 toll in KS between OK and Wichita accepts cash ($2.25).