I took some a couple of years ago. It's been quite a few years, so keep in mind that the info might be a little off.
I really liked both the tours we did. We did the day at Seaworld, and the Universal/Hollywood combo.
We were picked up at our hotel and brought to a central bus area. From there we found the bus we were supposed to be on (a little confusing) an were on our way. The only drawback I found was that you're stuck on the tour schedule, so if you'd prefer more or less time at any place, well too bad. OTOH it's very nice not to worry about the driving, the commentary can be useful/entertaining, and for the most part we found the time allowed at the various places just right. On the seaworld tour we stopped at some store that I don't know and had some time to look around. For us it was pretty useless, but that was the only down part of the tour.
I'd recommend doing one of their tours, especially if you're not familiar with the area.