HI A.,
My daughter turned 1 in January and we had a very successful Elmo themed party, so here's what I did for the kids:
1. "kids table"- crayons, coloring books (Elmo & sesame st of course), construction paper, stickers, colored pencils, markers.
2. On the table, had a list of games the kids could play themselves without adult supervision.
Some of the games were:
a) design & create a bday card for the bday girl,
b) word scramble (all words related to Elmo's world),
c) find the goodie bags hidden all around the yard,
d) guess how many goldfish in the fishbowl (Dorothy)- I used goldfish crackers.
3. Gave small prizes to the kids who won. I got "temporary tattoos" at Target for girls and boys for like 2.99 each.
As far as food, I had corndogs (costco bought), grilled cheese cut in shapes (this took a little work), potato salad, chicken & beef skewers, chow mein, fried chicken. All of the food was either home made or store bought. I don't know what your budget is like, but this was very affordable for us.
For the adult entertainment, I was lucky enough to have a Wii, and two playstations.
Make sure you have a set time also. Our party was 12-4 because it was after the little one's naptime and it gave just enough time for people to get in and out. You'll see.. it will be fine and the day will go by.
In the end you'll be glad it's over :)
If you need any other ideas, let me know and I'll give you more. I see that you have a lot already!
Have fun!!