Newark=more airlines...more options, true. Keep this in mind, though: EWR 737 trips are OFTEN early starts and late finishes. IAH has nowhere near the amount of non-commutable trips that EWR has. I have been at both bases.
I was advised by guys not to go to IAH because the folks there were much more senior. Well, EVERYONE was senior to me...whether by 1 year or 20, so it didn't matter HOW senior they were. I think what you need to look at is how many flights to your city are available every day. If you're just relying on Continental to get to and from work, I would try to get a feel for how many pilots and fas commute to that city. They are all senior to you and if there are a lot, then you need to look at the availability of other airlines.
I don't commute to Florida, but I think the commutability of IAH trips is a big factor. It's that different between the two bases. I spent a year in Newark and 90 percent of the time had a really early show and a finish after 6pm (then add the standard 2 hour EWR inbound delay and boom--no flights home that night).
Hotels in EWR are expensive and half the price in IAH. I had a crashpad in EWR and don't need one in IAH; I get about 4 hotel rooms a month and I'm conservative. Good luck...