The earliest that we could possibly get away from the SLC airport is 3:00pm; sunset on that date is 8:10pm. I'm concerned about driving toward Jackson as it is getting dark, amongst lots of trees from the south, Rt 89 (which I'm only recalling from our trip many years ago), which would make it seem darker than if we were driving "out in the open". It's at least a 5-hr trip, right? One in our group is a photography nut & might want to stop to take some pix somewhere along the way. I'm thinking that maybe we should only try to get to e.g. Montpelier, ID that first night, rather than push to get to Jackson in the dark???