The Ocean view Cafe/Grill on Celebrity's Infinity offers casual dining by reservation only on select nights - know for a fact they will not take reservations the last formal night! We tried - didn't want to get formal for the 3rd time!
You can call the restaurant or guest relations for reservations. We always made ours on the same day - no problem. Again, they are not available for service everynight - only certain nights.
The menu offers similar offerings to what is offered in the Trellis Restaurant. Perhaps 4 entrees, etc. It is to some extent a "buffet", in that when you are seated, they take the order for the entree and direct you to the bar to select your own salads, soups, then, at the end of the meal, you select your own dessert. However, on 3 of the nights we dined there, the waiter accompanied us to the bar and had us select our soups, salads, desserts, and he had then carried back to the table - go figure!
No tipping required. Lights are dimmed and it for the most part was not crowded and offered a lovely view of the ocean as we cruised - unlike the Trellis Restaurant.
Could almost forget that it was a part of the venue used for breakfast buffet!
I had lasagnia, chicken and strip steak. When you make the reservations they can/will tell you what will be offered on the menu for that particular evening.
Thanks. I must admit I never understood the rational of requiring reservations at the casual restaurant. Princess has a similar restaurant called The Bistro on all of their ships. It's open as a sit down full menu restaurant between 7:30PM and 4:00AM. Then it goes back to being a buffet. On the Sun class ships there is even music for dancing. The friends we traveled with on Ocean Princess were dancing fools so they LOVED the Bistro. No reservations, no tipping necessary but we always did because the service was so good.
You probably will find that there are various events associated with the formal nights that warrant formal attire. The first formal night, for example, usually is the occasion of the Captain's "Welcome Aboard" Reception & Cocktail Party before dinner -- obviously a formal occasion.
You don't have to buy three formal dresses. A lot of ladies bring one basic formal dress and various combinations of accessories (scarves, etc.) to make it look different.