You might want to try some of the scenarios posted at the Wargamer's Game Depot. Double Deuce has a fine campaign there. A number of others have also posted and some of the scenarios done since the publication of SPMBT are of the short "quick play" variety, not complicated but fun to play.
That is not to say that the scenarios in the game are not top notch. They are!
http://www.wargamer.com/gamesdepot/
Wild Bill