There are two routes from Boise to Phoenix. One is 93 south out of Twin Falls, Idaho, while the other route is I-84 to I-15 through Salt lake city. Each has their own characteristic...93 is single la...
I have used the 215 through SLC a number of times. Smooth sailing.
Towed through SLC on I-15 in a wet snow squall one afternoon. It was busy, all lanes full, traffic moving about 40 mph. Didn't find it "hectic"... not one accident or delay. Couple slowdowns at interchanges. They drive like they are used to it or something...
Sunday morning at about 7:00 a.m. is The Best Time to transit SLC....