you can find out for yourself on sources like http://www.airlinerlist.com
But anyway; about the 737
no airlines have all 4 NG
series. With the 600 and the 900 so unpopular even the club of 3 NG
-series flyers is quite small; Continental have the 700, 800 and 900, SAS the 600, 700 and 800 (although they are ditching some 800s), Jet Airways 700, 800, 900, Air China, Lauda and Malev all have 600, 700, 800. No US registered 600 though.
About the A-320, that's easy as only Frontier and Air France have 318s so far. With Frontier only having 319s, Air France has the full set of them now! Interesting to add Air France don't automatically buy all Airbuses, as they never bought the 300-600Rs and Air Inter disposed the 330-300s before merging into Air France, and they also don't take the 340-600, but they seem to like the single aisle versions.