The answer, in short, is absolutely. Planning and writing a menu in advance is key. For one thing, it keeps you organized. When throwing a dinner party, organization is key. If you're having 10-12 people over, most people can't just throw something together with what they have (unless you're really good and have a LOT of extra food around). Let's take a look at some other key points:
-Budget. Making a menu gives you a realistic idea of how much you would like to spend. For instance, if your budget is $100, what can you buy for the amount of people you are having over? You could probably make chicken, but steaks might be over budget.
-Assess your cooking skills. Have you made this particular dish before? Were you successful? If you decide to make a dish you've never made before, it's best to do a dry run about a week before. That way, you can make changes to the particular dish, or the menu. It makes the day of the dinner party a lot less stressful.
-See how much time you need to cook everything. You don't want to be in the kitchen the whole time during your party. You want to enjoy it too!
-Lastly, after the dinner party, look at the menu. What did you like? What did you dislike? Make changes accordingly, even jot it down directly on the menu. If the menu was successful, no harm in using it again! Next time, you know exactly what you need and how much you're going to spend, even if it's 6 months from now. Keep a folder with menus in it.
This should make a pretty good start to a dinner party. Remember, Organization is key!
Other links to consider:
http://www.foodnetwork.com/holidays-and-parties/servings-sizes-for-a-crowd/index.html -This link is key when deciding serving portions
http://www.gourmet-food-revolution.com/Dinner-Party-Menu.html - This link talks about balance and even availability of different foods during different seasons. Cooking in season can be much less expensive and everything in season tastes better too. It's a win/win!
http://www.epicurious.com/articlesguides/entertaining/partiesevents/menuplanning_food -Epicurios talks with Chef Gordon Ramsay about creating an allstar menu for guests! His main point, keep it simple!