runway12 is a freeware program you can add many objects to FS easily, they do have some aircraft, some of which are nice looking, others of which aren't so hot...but it's easy and permanent. The helicopters and ground equipment tend to look better than the aircraft.
http://www.rwy12.com/rwy12/ On the other hand, there have been discussions in the past of how to have AI planes pretty much just sit there on the ramps 99.9% of the time, making just a very short trip and returning, at perhaps 3AM
I'd say that considering the quality of the most AI models, this would be the PREFERABLE route, but it might not be as simple to do...ask the AI gurus!
http://www.evolveai.com/ EvolveAI has outstanding A321's and DC-10's,
http://members.at.infoseek.co.jp/FSpainter/ FSPainter has good widebody Airbuses and also the A319 and 20 planes, with tons of repaints. He's also got some really old and really new 747's, lots of B777's (quite high detailed for AI).
http://www.ai-aardvark.com/ AI Aardvaark has a massive fleet of Boeings (except 777), including 717, 727, 737's from the -200 to the 900, all flavors of 747 including the -400Freighter (hmm, except the SP, though there is a model for that made by someone else), 757, 767-200 300 and 400, all DC-9's, three Embraers the 120, 170 and 175, and MD's MD-80/90 series, and even one lone Tupolev TU204!
http://81.208.92.5/dee_cp/fs_projects/ Then, for GA planes (like Cesnas and Pipers), corporate planes (Gulfstreams, Hawkers, King Airs Lears and Westwinds), and also retro planes (DC-8's, 707, L1011's), then look up the works of Henry Tomkiewicz, Tom Gibson, and Dee Waldron.
Also, Henry Tomkiewicz has made some C-130's, F-16's, C-141 Starlifters and others, but you'll need to search Avsim or Flightsim for those, just punch in his name.
