I've been using Flight Explorer for a few yeas - $10/month for 10 hours. I seldom have time to go over the 10 hours, but there are additional fees if you do. Its a very good program. You can set the parameters for anything you like, i.e. all widebody aircraft landing at ORD
, or all inbound/ outbound for JFK
, or all SWA flights, or all 747's, etc. I have a setting called "rare planes" set for the AN
-124, AN225, Dreamlifter, 707's etc. I haven't tried any other programs on the market, but I've heard there are others. You may want to search the Hobbies or Photo forums for more info.