Let me start by saying I find poor reviews of this ship suspect. I think it's impossible not to have a good time on this ship. So if you are on the fence just book it and go.
We flew into IAH the night before from Philly. We stayed at the Homewood Suites IAH. I will say that the Homewood suites is a bit out of the way and there's nothing around it, I'd stay somewhere else. Although there's nothing wrong with the Hotel itself. We used Carnival's transfer from IAH to Galveston. It's an hour plus drive but the Carnival transfer was very easy and non stressful, yes it costs $80 each but honestly it's a no hassle way to get to the ship.
I was unimpressed with Galveston as a home port. There's nothing there, it's industrial and It didn't impress me as someplace where I'd like to spend time pre or post cruise. The sail out was marred by oil Riggs, not to pretty, I certainly prefer a Florida home port.
Awesome location, good value, great bathroom, good for 4 people