I don't have any experience in the regionals, in fact I'll caveat the fact that I have no experience in the airlines at all. So take my advice with a grain of salt.

That being said, I talk to a LOT of guys who come to Spirit from a regional, and without exception they are glad to be here. I'm sure the pay is below what they were earning, especially the first year but there are things that are just as important as pay. Amongst them is future growth, not just growth in an airline, but personal growth and expectations.

When I came to Spirit, I was not at all sure what to expect, but as I'm entering third year pay, the single biggest thing that pops out in my mind, the single biggest thing that made me realize that I made the right decision is this fact:

I look forward to going to work. I enjoy going to work and I enjoy being at work.

That's all I've got. You'll hear some incredibly rosy things about every airline and you'll hear some things that every airline sucks at. Spirit is no different, but when all is said and done, I can say I really enjoy going to and being at work, and that is worth a lot to me.

YMMV