I flew spirit just last week from MCO to DTW. All things being equal (times of flights and $) I normally go with spirit because I am pretty happy with their service (I think I have flown with them around 15 times round trip or so.) I find them for the most part a pretty flexible and reliable airline. They are less picky with the weight of your luggage in NW.
We are flying SW for the 1st time in a long time in March because I got great roundtrip non stop airfare.
We are flying to MCO again in May and I don't know what airline yet. This will be something to consider. Right now NW and Spirit are the same price. If we need more luggage then I will go with NW instead of Spirit. While this isn't a real big thing, it could very well result in me using another airline. I guess is Spirit notices a lot of that they might change back. I think I will send an email saying I am not pleased with the change.
When we flew last week we had 4 tickets and 6 bags. 2 of them were smaller, so I guess we could get a bigger piece of luggage and combine them if needed. I am cheap so I think that is what I would do. After all I fly Spirit so price does matter to me. Over all the entire flight experience was a fine one. In those 15 or so flights only one was really bad. One or 2 inconvenient ones, but not bad. We gate check the stroller every time. We could gate check the car seats if we needed to, I guess this is what we will do next time if we rent a car.
C.Ann, I want to be a once suitcase girl too. Oh to dream. When DH and I go just the 2 of us in March I think we will at least only have one then, but then again it is only for 3 nights. I think I can handel it then.