Hello!
There are so many wonderful restaurant choices in Epcot! I find that I tend to plan a lot of meals there due to all of the great options - especially in the World Showcase.
One of the places that I would recommend for a fun meal is Teppan Edo (
http://disneyworld.disney.go.com/parks/epcot/dining/teppan-edo-restaurant/) in the Japan Pavilion. This restaurant is hibachi style, and the chefs are truly talented and very entertaining to watch. The food is also very good.
Another very popular choice is Le Cellier (
http://disneyworld.disney.go.com/parks/epcot/dining/le-celier-steakhouse/ ). This steakhouse is located in the Canada Pavilion, and is modeled after a wine cellar. The specialties here include Canadian cheddar cheese soup, pretzel bread and a mushroom filet mignon.
I think that either of these would be great choices for a birthday dinner. I'm not sure of the ages of your children, but since neither is a character meal, they might be more entertained at Teppan Edo, since the chefs come out and cook in front of you. Wherever you choose to dine, I would suggest making your reservations 90 days from the start of your vacation so that you will have the best chance of getting the time you want.
I hope your husband has a wonderful birthday!