Do you have any of those foil chafing dishes in the stand that hold sterno-type fuel? There's a large pan of water, and then 2 smaller foil pans for the food - they stay hot really well. Put them in the center of the table so kids can't get near them, and put cooler dishes and plates around the perimeter. I use 3 chafing dishes for 6 items. You can pre-make the smaller foil pans and have 1 set in the one while others are sitting out.
I'd watch the soup-type things - they are apt to spill, which makes your clean up more involved.
Chili - vegetarian or with ground beef/turkey. Easy to make ahead.
Sweet & sour meatballs - I use frozen turkey meatballs without sauce, then make my sauce out of something tomato-based and something fruit-based. Sounds weird but it's delicious. Try chili sauce (or ketchup - very similar) and currant jelly (or apple or grape) - melt the jelly in the microwave, then mix with the chili sauce in equal proportions, pour over the meatballs, turn once during cooking. If you don't thaw the meatballs ahead of time, then while they are cooking, move the inner ones toward the outside of the foil pan (or do in a casserole and transfer to foil pan). This way they all heat evenly.
Your own mac & cheese - use any kind of smallish pasta like short penne or rotini and cook al dente. While that's cooking, make a white sauce (béchamel) with onions cooked in butter, then onion added until translucent, then flour (equal amounts with the butter -e.g. 3 T of butter, 3 T of flour) and whisk until blended. Add a few cups of hot milk and whisk until thickened but not boiling. Shred Fontina and Parmesan cheese. Butter the pan, add one layer of pasta then 1 layer of cheese, top with half the sauce. Repeat with the 2nd layer. Top with breadcrumbs or wheat germ mixed with melted butter, cook about 25 minutes until browned and bubbly.
Hot cheese puffs - these make ahead really well. That morning or the day before, split and lightly toast 1 pack of English muffins. This gives you 12 halves. Mix up 1 cup of good quality mayo and 1 cup of shredded cheese (cheddar, Monterey Jack, Pepper Jack, or any combination). Mix until you have a thick paste. If you have mild cheese, you can flavor it up a little with pepper or chili powder if desired. Spread the paste on the muffin halves, almost to the edge. Take a chef's knife and slice down through each round until you have 4 wedges each - 4 x 12 muffin halves = 48 appetizers. Put these on a cookie sheet - refrigerate until serving time. To bake, put in a 375 oven or even under the broiler but watch carefully so the top bubbles & browns but doesn't burn. Put on a serving plate and hand this to a friend to pass around! They will go fast so you don't need to keep them hot.
Mini cocktail franks wrapped in refrigerator crescent dough. I open the dough and separate the triangles, but then cut them with a sharp knife because they are so big. Put the cocktail frank at the wide end of each triangle, and roll up to the pointy end. Put on a baking sheet and bake according to the crescent roll instructions, usually about 10 minutes. Pass them with a small dish of grainy mustard or ketchup for dipping, or put them in a keep-warm pan on the chafing dishes and set a ramekin of mustard and one of ketchup right in the center of them.
There are plenty of great frozen appetizers at BJs or Costco or Trader Joe's. Mini-spanikopita (spinach pies), mini quiches, those little spirals made out of thin dough and different fillings (salami & cheese, ham & spinach, etc.) are so so easy to serve and they look cute.
Chicken tenders in several flavors or with dipping sauces: marinate in soy sauce, roll in sesame seeds (or serve with a soy/sesame/ginger sauce; honey mustard; dipped in egg and rolled in seasoned bread crumbs and served with a marinara-type sauce on the side, etc. You can cut the tenders into smaller nugget-sized pieces and serve with toothpicks.
Fruit kabob porcupines - hollow out a watermelon half, turn over and drain. Poke holes in the green rind with a metal skewer or a small sharp knife. Make a bunch of different fruits in bite-sized pieces (or let the store do this for you), using any color combinations such as melons, pineapple, green or red seedless grapes, kiwi, mandarin oranges and berries if you can find any that are affordable. If you use apples, dip in lemon juice to prevent browning. Avoid bananas - they get too soft and fall apart. Use the longer plastic toothpicks with an arrowhead-type point (holds the fruit better), and thread 4 or so fruits per pick, varying the order to make it colorful, then insert in the melon rind so the finished product looks like a porcupine. Put the watermelon half on a platter with kale leaves or any dark leaves, and consider a few paper towels inside to soak up any leftover juices.
I've seen photos (somewhere - you'll have to google it!) of cut up veggies in the shape of a Christmas tree, using halved grape tomatoes and carrot disks as "ornaments" and a piece of star fruit on the top, strips of red and yellow peppers (cut crosswise into rings which are then cut in one spot and used as "garland", etc. Serve with the usual hummus or bleu cheese dip on the side. Keep extra veggies in the fridge to replenish as needed.