Search through the old strings on this subject; you'll see a lot of advice and opinions.

Your guests don't have to decide anything two months in advance if you don't offer choices. You aren't required to; after all, it's just a dinner party writ large, and you wouldn't offer dinner party guests a choice of entree on the invitation.

I like both buffet and plated, and I've used both. Which is preferable depends on a lot of things, including but not limited to:

- number of guests

- size, geography, and "traffic lanes" of room (think this through carefully to avoid traffic jams and collisions of guests and servers for buffet service; don't laugh, I've seen this be a mess)

- formality of event (plated usually seems more formal)

- type of food (avoid sloppy for buffet)

Some people love buffets because they want to be able to choose exactly what will be on their plates; you can also (sometimes) go back for seconds. Others hate them because they hate standing in line and carrying their plates and glasses around, especially if they are wearing high heels and evening clothes they might or others might spill on.

Buffet breaks up the conversation at the tables, too. That's less of an issue if it's an event where most of the people are likely to know the people they are standing in line with, like a party, as opposed to a charity or business event.

Very important: almost everybody hates waiting in a very long line, and it will mess up the pacing of the evening if lots of people have long finished eating before others have even been served, and you have to wait ages to start the dancing. So I would only ever do buffet if you can have a very good guest (and server)-to-buffet table ratio: i.e., few guests or lots of buffet tables (not stations each serving different things, I mean several lines of the same buffet spread; if you are doing stations, then the same applies -- have more than one of each station). Make sure no one will have to wait in line longer than a minute or two and that dishes will be replenished before completely empty. I have seen otherwise lovely events completely ruined where the venue and/or hosts screwed this up.

In general, and I stress it's just a generalization, I'd say the smaller and less formal the event, and the fewer the items offered, the better buffet seems to work. It can work for a huge, formal event, but as I wrote above, there is an awful lot to do to make it work.

Have you considered "family style"? It is becoming more popular, even for very formal events. That's where the food (especially the main course) is served on platters to the table from which the guests serve themselves. The guests can pass the platters, or if you want to be Downton Abbey level formal, have butler-style service where the servers offer each dish to each guest (I haven't seen that). Our daughter had family style at her wedding, which was black tie, and it worked very well (and you can keep the leftovers, too!). Come to think of it, it was a real combination of types of service: during the cocktail hour, the appetizers were passed by servers and I think there were some on a table, too: the first course was served plated; the main course was family style; and dessert was sort of buffet: small pick-up style treats (cake pops, etc.) on a table near the dance floor (she wanted something people could eat while dancing).