I'd put this in a HOU thread if there is one, but I'll ask it here instead. Looking at the feasibility of a 5:30 am flight out of HOU. Problem is that the rental car return (National) doesn't open until 4 am and I'll have to catch the shuttle over there, check a bag, and then clear security. Do people think that that is a enough time at HOU? Or should I opt for the 7 am flight instead of the 5:30 am flight?