If you DO decide to bring it on board, you can't sit in the exit rows [with extra leg room] under FAA regs. I was on a flight that got delayed b/c no one realized that the guy in the exit row had a dog until we pushed back from the gate. Someone had to switch with him before we could take off. No one close by volunteered, and we ended up missing our take off slot, and having to wait an extra 30 mins or so.
