If you have more a buffet or a "food" bar she will be able to eat what she wants and other will also get thier fill.

Does she have a favorite kind of food?
Is she of a specific heritage?
You could plan an ethnic evening ie:
Mexican Fiesta
Make your own tacos, etc,
Break a pinata (the adults have more fun than the kids)

Japanese
sit on the floor
eat with chop sticks
do a temura bar and let people fry thier own food
(you get the idea)

Have wild west party
BBQ
do some line dancing
have a chili cook-off

Have fondue bar
variety of fruit & veggies
variety of fondue dips. ie: chocolate, Cheese, etc.

For a friends b-day one year we made our own subs, played group party board games (Cranium is really fun) and dipped our own candles. When we heard about it we thougt it sounded wierd but we had a lot of fun.

Does she like to cook? You could have a pot luck were everyone brings there favorite dish and the recipe on an 8 1/2 x 11 sheet of paper. Put the recipies in protective sheets in a decorated 3-ring binder and give it to her as a gift.

if she likes desserts you can have a dessert bar with the same idea.

I hope some of these suggestions will get the creative juices flowing.

Good Luck!!!!!!!

Why a surprise by the way? I'm not sure that's always as fun for the recipiant as the planners. If the guest of honor wants to look her best at the party, you haven't given her a chance to prepare. Also if the guest of honor tries to get some plans together for ger own birthday, she may find the friends you've invited giving her evasive answers or lame excuses about why they're busy. If it has to be a surprise because the guest of honor would otherwise refuse, then maybe you should think about what you're doing and give her the right to refuse.

But anyway, if you don't want a come and go party, then you have to space the events to get people to stay-- like is there a sit down meal, a card/ present opening time, or birthday candles and singing- with conversation time in between.

This isn't practical for everyone, but my parties always have a wide variety of people- veterinarians (I work at an animal hosptial), computer people (Dh is a computer game designer), family, neighbors, long-time friends. The way we keep people mixing is that we have a lot of things going on in every room. Our kitchen is tiny, but we recycle the bottles in there, so people mingle while disposing their bottles. In the dining room we set up a buffet table and keep several chairs around so people can chat while eating. In the living room we have a sofa and 2 chairs which usually are for people listening to music but sometimes we have karaoke. And we have a pool table in what was supposed to be a den. In the garage we have classic arcade games. Basically, there is something for everyone but we don't force people to mingle by having staged games or anything like that. People just get to know each other by waiting to shoot pool or play video games or getting food and drinks or singing or whatever. Like I said, not entirely practical for everyone (not too many people have pool tables and video games), but you could set up areas with different things to do in each one. I like having all the food and drinks in one place because it forces people to move around. That's what works for us, anyway.

Another friend has successful parties on a regular basis, with the vet crew and a lot of musicians and his other friends. We all mingle a lot too because he usually has the barbeque going (bring your own), horseshoes, badmitton, a bonfire, singing (real pros- a lot of fun to watch) and sometimes he gets us to bring the karaoke machine too. Same concept- lots of things going on for people to do without forcing people to play party games together.

In both cases, you never really want to just leave because there is so much going on all the time.

Good luck with the party.

When my husband turned 40 I gave him a suprise party but on the invitations I crossed the "0" and had a happy 4th birthday party. Everyone was asked to bring a child-friendly gift that could be donated to our local shelter, and the party was pretty much what you'd do for a 4 year old (excpet the beer... LOL!) -- lots of streamers and balloons, pin the tail on the donkey, pinata, limbo, big sheet cake with a clown on it. We had a DJ who played the hokey pokey and such among the regular music. Everyone left with a goody bag and I think the biggest hit of the night was the water guns...

Serve old people food as a joke: prunes, thin-sliced pepperidge farm white bread, and oatmeal.

How was the party?