The key to flying Spirit, Frontier, and Allegiant

Many folks ask me about flying supposed "low cost" airlines.  The fact of the matter is, their fares are ultra-cheap, and can get you to your vacation or business meeting in a more economical way than many other competitors.  But, what do you have to watch out for?  For one, these airlines are counting on various fees to make a profit (and it's working).  Here's a airline-by-airline guide to flying budget airlines in the United States.

Spirit

Probably the airline that gets the most press, Spirit Airlines flies to 57 destinations with 75 jets, with routes criss-crossing the country and journeying all the way down to the Caribbean, Central America, and Peru.  They're known for scandalous advertising, fees on everything (even water on board) and their unrelenting search for profit.

I've flown Spirit over 20,000 miles this year, and I'll be the first to say that I'll fly them again.  Their fares are super cheap (sometimes less than $30 each way), and I know how to play their game.  You can too!  Here are a few tips

Tip #1: Don't bring a bag. 
They'll charge you $35 to carry-on a bag, and $30 to check one. A personal item that fits under the seat in front of you, though, is allowed for free.  So, I try to fly Spirit on weekend trips where I don't need more than a change or two of clothes.  Don't fly them when you're going skiing or for that month-long backpacking trip!  If you are checking a bag, it'll be $5 cheaper than at the airport if you pay at booking.

Tip #2:  Buy your tickets at the airport.
Spirit charges $17 each way for tickets bought online.  That's waived at the airport.  Luckily for me, I'm located 30 minutes by public transit from the O'Hare terminal, so it's worth it to me to save the extra $34 (or more, if you have multiple trips to buy).

Tip #3: Don't eat on the plane.
They'll charge you for everything, and the options aren't that special.  They literally sell ramen.

Tip #4:  Don't be tall.
And if you are, know what you're getting yourself into.  I'm six feet tall, and my knees bang the back of the seats in front of me (seat pitch is only 28 inches).  You'll be tempted by the $25-$50 upgrade for an exit row or the "Big Seat" in row #1.

Tip #5:  Don't mind where you sit.
If you're a family that has to sit together, you better hope your fellow passengers are nice about moving around.  It'll cost you $10 (at least) to choose your exact seat on the plane.

Frontier

If I didn't scare you away with the stuff about Spirit above, welcome to Frontier!  This airline is a bit unique in that it used to compete with Southwest and JetBlue, with similar amenities, but switched to the ultra-low cost model a few years ago.  So, you'll actually find some planes with satellite television, better legroom, and comfier seats.  On my 5 flights on Frontier this year, I found it to be hit or miss what you're getting.  Other planes mimicked Spirit's 737s, with very thin, uncomfortable seats designed to jam as many people on the plane as possible.

Tips for Frontier mimic Spirit's.  They'll charge you for everything (except water, that's free).   And, bags are a bit less expensive, at only $25 for the first bag checked.  I also found it funny that I could change my reward flight for free up to two weeks before my flight.  They have a "Discount Den" that has been offering $20 flights lately, so join up if you live near their focus cities like Denver.

Allegiant

This is admittedly my least-favorite airline, and one that I've avoided for several reasons.  They'll charge you for everything as their competitors do above, but they take their cost savings one step further: they fly mostly from "alternative" airports.  So, you'll be buying a flight from Phoenix to Chicago, but think it's from one of the major airports.  In fact, they'll fly from Phoenix's Mesa Airport (a distance if you live in Downtown), and fly into Rockford, which is an 84-mile, $140 cab from the Loop and not served by public transportation, unlike both of Chicago's other airports.

For that reason, you're not truly saving the money you want by flying Allegiant.  While some "normal" city pairs exist, you'll run into problems if the above happens to you.  In addition, if your flight is canceled, they often don't have another flight until the next day (or next week), so you're stranded without a way of getting to your destination.  Be wary of Allegiant.