From SLC, one could take I-15 to I-40 then cross over to UT24 to Hanksville, but it is definitely much longer of a trip. US-6 from Spanish Fork to I-40 is four lane for a good portion of the drive to Soldier Summit, and is 65mph the whole way except near Price.
I-15/I-40/UT-24 : approximately 369 miles
I-15/US-6/I-40/UT-24 : approximately 231 miles
There are plenty of other variations to these too if one wanted to mix it up even more.
"Got tight last night on absinthe and did knife tricks. Great success shooting the knife into the piano. The woodworms are so bad and eat hell out of all furniture that you can always claim the woodworms did it."