Now that you brought it up: Don't leave anything unsupervised on the surface at Ginnie. Almost lost some dive gear, so did my instructor, until he noticed a suspicious pile of picnic stuff on a table surrounded by a bunch of teen / twentys party people.
One of my buddies had a gopro hero3 black stolen from his unlocked car at Ginnie a few weeks ago. There's definitely a lot of college kids through there.. some untrustworthy. Be smart and lock up your stuff.
Back to the issue at hand. The ballroom was one of my earliest dives. It was a lot of fun for me. There's some extra concerns due to the overhead but it's far from a cramped cave. I thought there was a lot to see. I've been twice (or maybe 3 times?) and I've got another trip out there planned.