I cannot say enough nice things about this organization! Please check it out. You visit during the night at feeding time. So if you're in town the night before the wedding this may be a good activity you could squeeze in while you're here.
Definitely worth getting tickets for both Universal Studios and Islands of Adventure. It's totally doable to finish both parks in one day, just get there early. Splurge on the fast pass if you can. My advice is bring your own water bottle, Wet-Ones, and patience. We love these parks and so does everyone else :)