BOI is the only major airport in the state of Idaho and has a very simple design structure, with one terminal divided into two concourses (A & B) and two parallel, side-by-side runways to the south of the terminal, 10/28 (L & R). The wait between aircraft movements seems to average about 5 minutes or more, and during slower hours, it can stretch to almost an hour! There simply isn't enough traffic at BOI to give it any worth for spotting.
-Concourse B: From the eastern end of the concourse, you can watch post-rotation departures until they disappear. Rotations can be viewed from the southern end of the concourse, with the rotation usually falling between gates 17 and 19.
-Walkway to Concourse A. Another good viewing area is from a walkway leading into Concourse A. From here, the last 3/4 of the 10 runways are visible, including the rotation point.
-As I have never spent any time spotting outdoors at BOI, I can't recommend any outdoor locations. They do have a parking garage, which I'm sue has a good view, but I've never been in it.
PRE-9/11 SECURITY REPORT:
Again, I have never done any outdoor spotting at BOI, so I can't say what security is like around the perimeter. Security in the terminals, however, is tight enough to close the terminal areas overnight.