The Getaway has been my families favorite cruise so far. I know you mentioned Syd's but I will say this has been the most fun we have had on a cruise. Its more of a show than just a cover band. If you want a seat, get there early.
I know you didn't mention it but pass on American Diner. Its not great.
For MDR, go to the Tropicana. There usually isn't a wait like there is with Taste and Savor and they have live music. The atmosphere is as close to how you would picture early cruising.
I don't know your groups physical ability but do the rope course if you can. Its one of the best ones at sea and they have a walk the plank where you walk out about 5 feet over the ocean on a thin rail.
O'Sheehan's is great for a late night snack. We even went back for an adults dinner on another night.
If there are kids in your group, you can buy an unlimited arcade pass. They can use it on the video arcade and also the games in O'Sheehan's.