One of the best flights I've ever taken was Spirit and had 8 passengers on it, 5 of which were transferring staff/pilots. The second worst flight I've ever had the pleasure of enduring was also Spirit - the worst was Easyjet (simply because their seat dimensions are somehow smaller than the average human and generally incompatible with human physiology), and third worst was Ryanair because a mass of orange colored Brits are with near a unlimited supply of duty free gin is... amusing enough to move it up a few notches.

> a mass of orange colored Brits are with near a unlimited supply of duty free gin

I fly direct from London to Vegas occasionally. The upside is that going through immigration is trivial -- of 270 people on a flight, 265 go to the "foreign passports" line. The downside is the 15 minute wait after getting to the gate for the police to come and arrest the people who were fist fighting in the aisle.

I've flown on Spirit exactly once, thanks to an ex-wife who fit the "needlessly frugal" type talked about yesterday to a tee. Grew up in foster care and couldn't acknowledge we weren't poor. We flew into Miami during some bad weather and it's the only time ever in decades of flying I've seen the flight attendants visibly scared. If you've ever gotten speed wobbles on a skateboard, it was just like that. I'm still amazed the plane didn't fall apart in the air. They also charged for water.