I hate to be a party-pooper, but you are so close it may be hard to get anything.
My first thought is Chef Mickey--- we love it and there is nothing like the Disney feeling you get there. Definatly do it once before you leave!
We start our first night at Whispering Canyon Cafe. While there are no characters (in costume anyway, many of the servers are "characters"), it is a lot of fun, silly and the reason we do it our first night is because is does put us in the Disney spirit.
I agree the castle would be great, if you can get in. And my husband and I always wanted Cali Grill, and thought we'd add it for the 2 of us this year (as we just celebrated 15 years of marriage), but I didn't think about it back when I made all our ADRs and despite calling everyday, I have not been able to get in before 9:45pm. I wish you luck, and be persistant, people's plans change all the time, so things open up all the time. I wish you luck and no matter where yo ugo, you'll be in Disney, there will be spirit no matter where you are...