Just a quick search on Airbus shows that A320 with the current highest gross weight would be limited to 150 pax and luggage to a leg of 2300-2400 miles. Considering the fact that JetBlue has 168 pax configuration I think this will come with some weight penalties on long runs like JFK-SEA. Currently only UA is serving that market with A320s besides JetBlue and they have less seats per plane. A321 on the other hand has a longer body that enables the additional fuel tank option. But this again contributes to the weight and makes the airplane heavier. With the JetBlue's only coach config , I think it can easly hold 190 people (Airbus lists it at 199Y config, but I don't think JetBlue will be interested in that kind of a tight configuration). Fully loaded A321 has only 2300 mile range which makes it a bit short of some JetBlue routes. BAHA Fan of a naming contest : A320-300 or A320.5 :)