Dining hours are always a big question. The big advantage of anytime dining is that you don't have to rush back to the port and get ready for dinner after a big day ashore. For example, in Skagway I can remember getting back to the ship about 5:30 after having driven all day and visited the dog camp and so on. A couple of hours to relax and clean up was welcome. OTOH there might be a night when you want early dinner and the early show and off to bed so you can be up at 5 AM to watch the entry into Glacier Bay where whales are often encountered.
As far as the Sabatini's menu ... the waiter will say, "Just pick out your entree. We will bring you ALL the rest!" It is basically a tasting menu with a small serving of everything on the menu. We have never done lunch there but it should be fun too. The only thing is you will be busy on port days, and on sea days it will book up fast.
Have a GREAT cruise!