I did what I thought was a bunch of prep, and the question that stumped me was "why spirit". I bogged down in BS answers about how it's a "fun" company and fun and hey yellow and fun!!!!!111one. What a load of crap. Look at the investor slides and come up with an answer with some meat behind it. Right now, find that article that shows how the ULCCs are leading the post-covid recovery with seat capacity, ahead of pre-covid 2019 numbers in some markets. Spirit is a STRONG company that isn't relying on stealing market share from other companies in order to meet it's growth goals. Point THAT out while mentioning that it looks like a comfortable growth-minded place to be (with a real big-boy contract!) and a "destination" job not just a stepping stone to somewhere else, and you'll stand out. Don't EVER hint that your career goal is 777s to Europe or Japan, they're looking for quality career pilots who are interested in joining a company that is essentially printing money as fast as possible to give to it's employees while they grow as fast as they can hire. You can mention no hats and no double-breasted coats as a more comfortable workplace, but that's only part of the picture. If you can throw in how your previous instructor background may come in handy to help the company grow, that could be a big help too.

I figured this out AFTER I got hired, and realized how close I'd come to making a HUGE mistake in the interview process by not knowing what they were really looking for. Coming from a military background I had nothing to compare it to so I regurgitated their corporate branding about Spirit being a fun airline to fly on, and then pointed at my resume that showed my instructor experience. It worked, but I was lucky. A more informed approach might be better so don't fixate on the yellow fun factor. It's a ULCC that creates market share wherever they go, the company leadership is solid, and the contract proves that they value quality employees. And your experience fits right in with what will help the company keep doing its thing.

Also, the pilot group has a reputation as being good people, friendly to non-rev jumpseaters and other airline commuters. Those are the people you want to spend your BEST years with, not a bunch of egotistical goobers flying super heavy trans-continental triple whatevers.