A FlyerTalk Posting Legend
Join Date: Jul 2002
Location: MCI
Programs: AA Gold 1MM, AS MVP, UA Silver, WN A-List, Marriott LT Titanium, HH Diamond
Posts: 53,010
I've had a spreadsheet forever, but Miletracker does very well, so I don't monitor my spreadsheet in as much detail anymore.
It stores all the data I need, and you can jump to the airline website easily if you want more information.