For age 3, Keep It Simple is your mantra! You can do just about anything, just call it Princess So and So! Boys can come, for sure--they don't mind. Let's be clear: eveyone likes a party!

I might recommend a party that lasts about an hour and a half.

Step 1: Some sort of activity, with parents' help. This can be decorating a paper tiara or crown (collect cereal boxes, and you can make the template yourself). Boys and girls wear crowns, so you're in the clear, here! (15 mins, recognizing that some kids are going to wander off! No worries, just let them go with their parents. )

Step 2: Make a castle! Haul out some big marshmallows and toothpicks and let kids create castles. Only about 10% of them will actually look like castles, and about 50% of the mallows wil be consumned, but so what. Provide little toothpic flags at the end so kids can top their castles! (15-20 minutes)

Step 3: Now, everyone's hungry! Provide a little savory meal with princess decorations. (15 mins)

Step 4: Dessert comes out! Everyone's favorite part! (15 mins)

Step 6: If you're so inclined: Open presents. (10 mins, if the party's small)

Closeure: Dance party with balloons! Princess-freeze dance or just plain old dancing. Kids love this. Follow the leader type dances are good. Putting bday girl in the middle and letting children dance around her is good. You know, some special attention stuff. Take lots o' pics. (15 mins)

Good-bye: Every child takes home their crown, marshmallow sculpture in a bag w extra 'mallows and 'picks, and a balloon. The end!

regarding the pull string pinata... look for the one that is the dragon. We had one at our princess party (7+ years ago). I think we found ours at Party Warehouse (Brookville Road in Silver Spring)

At that age the kids will also just want plenty of run-around time. Decore well & provide props but don't schedule too many activities - they will enjoy the pretend play around the theme of the party. The boys can be knights - it's an equal opportunity theme.

For an outdoor play idea for that age, you could get bubbles for everyone and have all the kids blow bubbles. I think that would be cute and fun for the little ones.

We found a bunch or really cheap stools and ikea and decorated them with different colors of shiny fabric and ribbons (with hot glue that then pulled off so they could be used for other things). We used them to play "musical thrones." I spray-painted a bunch of old boxed gray and cut holes in some for doors and windows and had the kids build a castle together (threw some old bedsheets into the mix and it was a big success).

I spent $20 on foam crowns and tiaras and gems to decorate them. It was a big hit.

http://www.amazon.com/Adhesive-Back-Jewels-500-pc/dp/B003AHBOMS/ref=pd_sim_sbs_ac_2

http://www.amazon.com/Darice-105047-JP-Foam-Crown-Wrap/dp/B002JQ06X4/ref=pd_sim_sbs_ac_3

(don't buy the crowns/tiaras from Amazon, they are only $1 or so at Michaels).