There are three main runways at IAH- 8/26 and 9/27, which stradle the airport on the north and south sides, and 15L/33R, which runs along the west side. There is also a 15R/33L, but it is too short for anything but prop-jobs. Departures seem to occur mostly on 15L and 26, with most arrivals coming on 26 and 27. Continental obviously makes up the bulk of the traffic, which can make things a little boring at times. An underground train which links the terminals makes moving around the airport easy, which comes in handy when spotting from the parking garages.
-Terminal A Food Court. Planes waiting to depart on 15 can be viewed from the food court in Terminal A, as can arrivals on 15, but the birds will be out of sight by the time they rotate.
-Terminal C Food Court. Similar story here. Can get a good view of arrivals on 26 and planes waiting to depart there, but most rotations are out of view.
-Any Of The 4 Parking Garages. Each terminal has its own parking garage, and each are very good for spotting. Term. A garage is the best place to watch the action on 15/33, Term. B and C are good for 8/26, and Term. IAB garage is best for the distant arrivals on 27. Unfortunately the top floor of each garage is the only one with a clear view, and in the hot, humid Houston weather, you might not want to stay long.
-Lee Rd. Spotters' Lot. Right at the end of Runway 27 on Lee Rd. there's a public parking lot that provides very good views of arrivals on 27. Takeoffs are pretty evenly split between runways 26 and 15, with a few elsewhere, but most of the larger aircraft arrive on 27, and this lot gives a great view of it.
PRE-9/11 SECURITY REPORT:
-Security at IAH may be some of the friendliest anywhere. In the parking garages they will drive by every so often, but never do they say a word. Lee Rd. parking lot is specifically designed for aircraft observation, so there's obviously no problem there. Spotting at IAH is made all the more enjoyable by security's friendly approach towards spotters.