Southwest is the most successful airline in the country precisely because they have resisted the urge to mutate, or grow in risky ways:

** One, count 'em, one, aircraft type.

** They're not duking it out in ORD or LGA or JFK or ATL or BOS.

** When they open a new city they pick it very carefully, then go in for the kill. They don't dabble with two or three flights a day; they run a blitzkrieg. They don't aim for a few market share points; they either create a new market (MHT) or transform one (BWI, where they decimated a US stronghold).

** No "marquee" or "prestige" routes that would earn attention and maybe full planes, but no money: HNL or LGW, for example.

Southwest sticks to their knitting and aims to kill. JetBlue doesn't seem to have that discipline down yet.

I live in SEA where B6 has just two flights a day: redeyes to JFK and BOS. They don't advertise here. They have almost no visibility here. The aircraft are only seen here between 1000p and 1200a and the modest check-in desk is unmanned all day long. They're such an afterthought here that when I was being scr@wed over by DL a few weeks ago and absolutely, positively had to get to BOS in a hurry, I didn't even think of B6 until it was almost too late. (And I initally booked a seat to JFK plus a rent-a-car... I did not even know B6 served BOS direct from here until I walked down the concourse and saw the other flight's gate signage! And I pay closer attention than most to what's up at Sea-Tac.) I daresay other JetBlue west coast stations are in the same situation.

I would LOVE B6 to build a real presence here in SEA but it'll take more frequencies to the east, new service down to OAK and LGB, and more marketing. Southwest is solidly entrenched in SEA; B6 is an afterthought.

So forget a third aircraft type and work on building up the stations you've got with the aircraft you've got.