We went in August, and I'm sure that had a lot to do with our experience. It was the single hottest themepark I have EVER been in. I grew up in Southern CA and visited the Sea World in San Diego too many times to count as a child/young adult. I always loved it, so when we went to Orlando the first time I jumped on the chance to go.
There is very little shade so very little relief from the oppressive august heat. It was extremely crowded and they seemed understaffed. The shows required a line up up to 1 hour in advance, just standing there in the heat. If you weren't in line then you didn't get in because the stadiums filled to capacity so quickly.
Now, this was back in 2001 so it may be much different and you may be going at a less high-demand time of year.
I think I would base it on how much you think each individual member would get out of the trip. How old is your son? Our preschool aged child who adores anything aquarium related did not enjoy Sea World because it was too much waiting (waiting to get into shows, waiting for the show to begin, etc) There was almost nothing to keep her attention for more than 5 minutes the entire day and this is a child who can spend hours on a single project.
We will go back but probably while we are in Southern CA visiting family and not to the one in Orlando. I don't want the post to turn you off completely, it's a wonderful educational opportunity and the animals are beautiful and well cared for. We just didn't get $50 worth of enjoyment out of it!