My neighbor did this trip--from west coaast into chicago and on to La Guardia via ATA. felt it was not well organized-changed departure gate at last minute,ended up in "C" group for boarding and her baggage arrived one day after she did...
Now questions if she should have just gone all the way on SWA into Long Island??
Any opinions???
Was a Rewards ticket.. (free RT)

Not sure what you are asking exactly. Is it better to fly Southwest to Long Island vs flying ATA into LaGuardia? No idea, guess some of that depends on your neighbor's ultimate destination. I happen to love Southwest Airlines, however, so I can recommend them as an airline, at least. Never flown ATA.

It would really depend on your final destination.

ISlip [Southwest airport] on Long Island is a really long drive into Manhattan, especially if it happens to be rush hour [or the reverse for the flight home]. If you want to go anywhere in NY beside LI [Westchester county for example], LaGuardia is a way better choice.

I flew from/to Islip once when I lived in Westchester County and it was awful -- 2 + hours.

Deb

ATA is NOT Southwest airlines, even though they code share on certain flights. SWA flies all Boeing 737
with seat pitches 32"-33" while ATA can fly both Boeing 737 and 757 with seat pitches ranging from 29-33". That said, I always find the seats better (wider and more knee room) on Southwest.
As was mentioned, Southwest code shares with ATA into LGA and I think Newark. Unless you are using points or miles than I would suggest another airline, or fly SWA direcyly to either PHL or ISP.

Flying into Islip is a really bad idea unless it's saving you many hundreds of dollars. It's very far from the city (really for the millions that live on Long Island) and transit back and forth isn't good.

You will need to leave the city at least 4.5 hours before any flight out of Islip - since the trains run only once an hour, take the best part of an hour and a half, then you need to find a cab or shuttle (every 30 minutes) to the airport.

Car service CAN be faster - as long as you don;t hit any of the rush hours - but is over $100 plus tip and toll.

Sorry - LGA to midtown by cab is about a half hour unless you hit rush hour.