Barcelona - 60th Birthday Dinner Suggestion?

Just some advice, (any recommendations I would have for Barcelona would be outdated) keep in mind that in Spain, most areas do the big meal at ~2:00 PM and eat in the evening, something lighter, not before 8:00 or 9:00 PM...so a big dinner might be closer to what you would consider lunch, especially if eating at 10:00 PM does not settle with you.

For a view, there may be some good options in the Barceloneta area, particularly if you like seafood; or along the harbor. Further away from the shore, there are some rooftop or "sky" restaurants that boast a view.

If you are partial to Michelin's recommendations (not for me honestly, but many like them) there are a bevy of Michelin starred places (nearly 20) to choose from.

I have three suggestions :)

Seaside Escapade
About 25 min train ride south of Barcelona is the laid back costal village of Garraf, popular with locals and with several good seafood restaurants with stunning views of the sea. I'd recommend the restaurant La Cúpula Garraf, it has commanding views of the Mediterranean, their specialty is a fantastic Fideuà and an excellent chocolate pyramid for dessert! https://lacupulagarraf.com/

Harborfront Paella
Overlooking the old port and Barrio Gotico is the restaurant called Barceloneta an upscale establishment with great views at night, local Catalan seafood themed menu with some of the better rice dishes in Barcelona. https://restaurantbarceloneta.com/en/the-restaurant/

Michelin Star Experience
Consider Àbac a three star Michelin restaurant, one of the hottest places to eat in Barcelona currently, lead by the innovative head chief Jordi Cruz, who is a bit of a celebrity in his own right in Spain due to the very popular MasterChef tv show. https://abacrestaurant.com/en/#home

PS:
I 100% agree with Paul, lunch is the main meal in Spain, you'll have the most flexibility and options making it a special lunch (2 pm) rather than a dinner (10 pm+).

You'll find most restaurants don't even start to open for dinner service until "late" like 9 pm, or they may not open at all for dinner certain days. Plus the dinner menu may be more limited than lunch.