When I went to Alaska in 2006 from Ct. for 3 mos I made no reservations even though I planned the trip and all the stops. What I found is that once we started hitting the NP's some we really liked and stayed a few more days, like RMNP, YNP and Glacier NP. The trip through BC Banff, Jasper, Muncho Lake and Kualane NP in the Yukon all required additional days. The trip up to Alaska was just as nice as Alaska itself. A lot depends on how you like to camp and what you like to do. I like to fish and camp in more remote areas either by a stream, or lake. Some of the best camp sites were the pull offs or NF CG's. If you want FHU's you may have to make reservations on the WE's or holidays. Have fun on your trip