Folding bikes and airlines

I just ordered a Downtube bike. I fly every once in a while and there are a few places I want to go just to explore by bike. I've been online checking out airline policies and they vary a lot! United is actually only allowing one checked bag soon, $25 for the second one. I wonder if this is going to be a trend? If you have a bicycle on United, even if it is in a regulation bag you have to pay $80 now and $100 after May 1st. American and Southwest seem to be friendlier. If your bike fits in a regulation suitcase, then it's part of your checked bag allowance. Right now that's two bags. I didn't realize before that I will need to really educate myself before flying.

Any stories or more information about airlines and folders from anyone?

I never paid fees traveling with a bicycle that fit into an airline legal case (both suitcase size and weight), both bike fridays and s/s coupled full size. But, I would also not declare it as a bicycle, but as bicycle parts since it is always partially disassembled so it is also honest to call it bike parts. With the new 2 suitcase rule, I would put my bike in one case and my regular luggage in a carry on if I could fit it. Otherwise, I guess $25 isn't too awful if I really needed the stuff, like for a tour. In fact, with my s/s coupled bike, I find its easiest to pack it into 2 suitcases together with my clothes, less disassembly required, so I will probably continue to do this and pay the $25. It still beats the fees on a full size bike box (closer to $100 on most airlines).