When I look back at those days when my children were under 5, the party is really for the adults to congregate and let the children play. The kids don't need anything fancy, just a supervised, fun activity.
By the way...the pizza and cake thing has to go!
Party venues are expensive; and they offer the junk food we really don't want to feed our children, the adults usually won't touch it...making them wish they were at a nice restaurant instead of Chucky Cheese. Getting my point?
Is your house and backyard big enough to host a few adults and children, so they can swim, play in the sprinkler if you don't have a pool, or you live in a community with a clubhouse?
Set out on the dining room table (inside where it's cool) an assortment of finger sandwiches and fruit, crackers and cheese and provide water for the kids and perhaps beer and wine available for the adults. The traditional cake will provide enough sugar for one day.
And then we were obligated to have party bags. What a waste of money. One parent put permanent markers in a party bag that she gave to my son. Use your imagination on that one. He went crazy decorating the furniture and walls! It was my responsibility to go through the darn bag, though...
Hey, a few balloons make it festive; but the bottom line is that the children don't care about the clown or the venue, nor the party bag and decorations galore; but your adult friends will appreciate the event if it's more intimate vs. commercial. That is because they should be present to supervise their own children and others if need be. At that age, no child should be dropped off for you to supervise. That's another nightmare story to tell at another time. Have fun and make it a fun, simple and memorable day for you and your family and friends.
Blessings