No that doesn't sound daft at all, my reasons for always staying in Epcot area resorts are because I worry I'd miss it if I was elsewhere!
Discovery Cove is awesome, we did it in 2008. Loved the snorkelling, the birds and the stingrays and the dolphin swim was magical. I still have the dvd we bought of our swim but I haven't watched it in ages. You will love it! I had bad sunburn and the birds landing on me was painful but other than that slight error on my part it was absolutely fantastic.
We're going for the 14 day ultimate tickets too, can't beat being able to go between the parks all day. We are also going to do Universal because my sister has never been, she's looking forward to the WWOHP and I'm looking forward to seeing her face when we get there. The Forbidden Journey ride was the best I've ever been on.
Other than that might do Seaworld, I'm looking into the Beluga whale meeting as a surprise for my sister but not sure yet. It'd be like $300 for the 2 of us which is a hefty price!