Sea World is the best park in all of Orlando IMHO for those who are not into thrill rides. They have some great coasters, but what SeaWorld really specializes in are shows and animal attractions (and those are wonderful!). On our next trip to SeaWorld my cousin, me, my nephew (who isn't doing coasters for the moment due to some back issues) and my son are doing SeaWorld for a day. The only one who will be doing any of the thrill rides will be my son (ok -- I will do one ride on the Manta too.). My son and I are doing three different parks on a mini Orlando stay and asked my cousin and nephew who live in Tampa and Orlando respecitively if they would like to join us one day. They said yes and both picked SeaWorld because it is such a great day and not ride based.
We love all the Orlando parks, but FYI for both me and my son, SeaWorld happens to be our favorite too. From what you are saying, I would strongly encourage you to try it out.
Plan your day around the shows (pick a time to do the Dolphin, Orca, and Sea Lion show and do the animal exhibits nearby in between. Also (but not just have the Orca show lets out, check out the Wild Artic. That one has a simulation ride if you do those. If those make you to Dizzy, they have the movie by itself and after that, you go to the wild artic area. The Penguin encounter that has a ride is not really a thrill ride and you should be fine with that.