Restoraunte' Party Invitations: Use "Formal" Dinner invitations.  They should state that  the dinner is being given "In Honor of -name-", birth and date.   Request formal attire.

Decorations and Setting Up:
Menu:  Make on the computer and place in clear report cover.  Make one for each child.
Name your restaurant.  This idea uses Italian as a suggestion. 
Course selections-list several to choose from.  Make very fancy. 
  Hour devours
     Assorted Green Vegetation with Dressing (salad)
     Milk Curds with Fruit (cottage cheese and peaches)
     Melted Milk Curds on Flat Bread (cheesecrisp)
  Main Course
     Spaghetti
     Lasagna
     Peanut Butter and Jelly Supreme (just in case)
Beverage
     Sparkling Grape Juice
Dessert
     Your child's favorite
Set up the table: 
     Table cloth, mints, candle(s), Real glasses and plates
Staff (or your those that will help you)
     Waitress
     Cook
     Coat Checker
     Bus People
Serve the Dinner as it would at a real restaurant.  Place the napkins in the children's laps, take their orders, turn them in to the cook, etc.

Goodies To Take Home:
Menu
After Dinner Mint

Other Activities:
Piñata or other kid style party games