Welcome to Cruise-Chat! We have been on two Princess cruises to Alaska. It is fantastic!
I'm not sure what kind of dining information you need, but I'll tell you what we usually do. We like to eat early, so we do the "main dining" rather than "late dining". Our friends prefer the open seating that you have chosen. It's nice to have all these choices!
We eat breakfast and lunch at the Windjammer Cafe. This gives us the opportunity to eat whenever we want. There are numerous other places around the ship where you can eat lunch, also.
If we have an early excursion scheduled, we order room service because it saves time.
I don't know where you live, but if you will be flying to Seattle, I always recommend arriving a day early and most people on this board will agree, I think. First of all, Seattle is a neat place to visit. But more importantly, it buys you time in case of flight delays, lost luggage, etc.
Have a great cruise!