Not sure why your party starts at 3 PM...frankly I resent parties that take up my whole day. I'd much rather a party start at 6...especially if it's going to be a meal.
By all means have music.
I would serve snackies like cheese puffs or vegetables with dip, perhaps a cheese ball, with the cocktails before dinner....and then after about an hour, put out the buffet and set up a separate dessert/coffee station.
I would not try paella for 27. Paella needs to be served very soon after being made or it turns into a sticky mass. How about lasagna inseatd? Or a baked ziti?
Have fun!
Linda C

If the party overlaps a meal time I think you need more than appetizers. 3:00 is sort of an odd time to start. If people have kids it may be an issue (everyone we know has hockey or wrestling on weekend days).

Spiral ham is pretty easy. It was a big hit at our New Year's Day party, which was a buffet. And it is very easy for you. The two hot dips went well. The salmon pies (a French Canadian specialty) were a HUGE hit, and easy for you. If you are interested I'll write the recipe here.

Do you have plates, glasses, flatware, etc. for that many?

Personally, I wouldn't do a green salad for a buffet. But that's me.

Would that be a seafood Paella? Not everyone eats seafood, and some are very allergic to some forms of it.

Usually, a buffet implies there will be choices. Especially with a seafood main dish, I'd do another meat--the spiral ham is a good idea that won't involve a lot of work. And a hot side dish or two--they can be simple--maybe green beans almondine, or California Mix veg. And if you're doing salad, what about a salad bar? Big bowl of greens with several smaller bowls of toppings and assorted dressings?

I'd just be afraid, with the menu you're planning, that there will be some people who won't find anything they can eat--there aren't any alternatives for the person who cannot eat fish or rice; or who may have a health condition that prevents them from eating salad. You definitely need a second meat and some cooked veg. to be on the safe side

I had an open house from 3 to 7 sunday Dec 30 and most of the people came around 5. I wouldn't have a birthday party that started at 3 because you would want everyone there at about the same time, not coming and going like an open house.
but I guess you already sent out the invitations, so I would suggest you have stuff that can stay in good shape like a ham or sliced turkey, salads and the desserts sound great. I just think a paella gets served at one time, its not buffet fare. Seafood is fragile and needs to be served at once in my opinion. I remember once serving cioppino the San Francisco favorite fish stew and it was less popular than I would have guessed. If you live in California or like sushi its easy to think lots of people like fish, but some don't.
Pulled pork stays warm in a crock pot, you could try a chicken dish with rice. Good luck.,

I see what you guys mean by the time, but there are reasons why I chose the odd time. Every time I'm invited to something it's usually between 1 and 3, so I figure that is what the people I'm inviting are used to doing. Only one kid coming and she does not do any extra-curricular activities.

I live about 45 minutes from almost everyone in our family and circle of friends and would hate to have a late party then they have to leave early just to drive home. I know all of them very well and they are not night owls like I am, so I'd rather them come at an odd time than not be able to come at all. This was the biggest reason for the 3PM party.

I have changed my mind about the paella (thanks for the info I did not consider before). It's way too much work and too expensive for so many. I'm going with Italian and I'm having it catered. I'm making everything except the main dishes. I figure a couple hours of appetizers and drinks and then an early dinner plus dessert and birthday cake.

I'm still planning so thanks for all the input. It helps out a lot !!