Here are my very quick thoughts:
Doing / info - A little bit vague to make a strong brandable domain, at least it's short and a dictionary domain, can't see obvious use.
TRAVELPRICEFINDER /com - Would look OK in the SERPs, has connotations of finding good value, which is good, nice extension. A bit on the long side to be highly brandable which doesn't help domain value.
SEATFLY /com - Almost a good domain, but it doesn't quite communicate the product the way you'd want it to. Nice and short though.
Rgds