Well, if you had said you were coming to San Francisco I could easily help you. SLC...I'm not so good with.
That said, I recently passed through Salt Lake City on my bike and stopped in at the local Triumph dealer. (also BMW dealer) They are actually located a bit south of SLC in Sandy, UT. http://www.triumphofutah.com/
Although I don't think they actually rent bikes, in the same complex as them is a rental shop that had BMWs out front; they might have Triumphs as well - I didn't go in to ask. It might be worth a quick call to Triumph of Utah to see if they can point you in the right direction.
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