How about a Chorizo stuffed Pablano with Smokey tomato Sauce and toasted Pepitas??

http://bit.ly/z9xx2w

This recipe is vegetarian, but if that's not your thing you could easily do substitutions.
www.rootpursuits.com

Butternut squash is a great filler, too. Use oaxacan cheese if possible. Or maybe even ground turkey, wild rice, raisins, and walnuts, and goat cheese.

My dad's fried in egg chile rellenos are too labor intensive and get cold too quick for a party.
A chile relleno casserole works great for informal gatherings. The pioneer woman has a good recipe.

Chile relleno are very laborious, so the more simple, the better.

The recipe I use is adapted from my best friend's mother, who is from Guanajuato, Mexico.

I char anaheim chiles, remove the skins, and de-seed by scooping from a slit in the side of the chile. Then, I stuff with a chunk each of jack cheese and queso fresco (crumbles fall out too easily). I dip the stuffed chiles in flour, and then frothy eggs (I first beat egg whites, then add yolks when stiff- 1 egg per 2 chiles), and shallow fry in vegetable oil. Drain on paper towels, and finish by adding fried chiles to tomato sauce made by simmering then blending a few roma tomatoes, a little onion, garlic, and caldo de pollo (powdered stock).

Sounds simple. Takes forever. If I were cooking for more than 10, I'd turn it into a soup or casserole! Good luck!

The one and only time I tried to make chile rellenos, it was such a disaster that the dogs would not eat the mess I made. I haven't had the heart to try again, NATKAHN's recipe give me hope :)

I made this recipe from Girl's Gone Child's blog (recipe by her mom) once. It was so delicious but was a lot of work! Anaheims definitely work the best, other peppers may fall apart (as I sadly learned). She gives multiple filling options!
http://www.girlsgonechild.net/2010/08/eat-well-www-say-peter-piper-come-pick.html

I have a recipe for chiles en nogada which I serve at room temperature, so it might be good for a party:
http://tandooritaco.wordpress.com/2012/01/02/chiles-en-nogada/

a little late, but I posted black bean and goat cheese chile relleno on my blog about a month a go. check it out!