Favorite dishes for weeknight entertaining?

These are my go-to's because they can be prepped or made ahead and always get rave reviews:
http://www.food52.com/recipes/13566_green_chili_chicken_posole_soup from dymano
http://www.food52.com/recipes/10695_flambed_chicken_with_tomatoes_and_garlic by Chef June
http://www.food52.com/recipes/2962_secret_ingredient_beef_stew by smallkitchencara
I also make a very elegant halibut En Papillote with a crab sauce that is a show stopper. The recipe comes from Shirley O Corriher. If you want me to send it to you, send me a message.
Cheers!

Thanks so much to everyone for weighing in. I really enjoyed reading your answers, and I've saved your suggestions to my recipe box!

I really love to serve chicken (braised spatchcocked whole or pieces depending on how many people are over) since you can really vary the seasonings with what you have on hand and it makes a nice presentation served over greens, spaghetti squash, cabbage, or any starch. Also, cooking chicken covered on the stove frees up the oven for making sides (or dessert). I have made chicken paprikash like this (essentially chicken pieces braised in onions, stock, and paprika, finished with sour cream) in under an hour and it was a huge hit.
We also like to do crostinis since you can top with cheese, cured meats, hummus, pesto, again whatever you have, and most of these topping last awhile (meaning I always have an assortment in my fridge and need only to pick up a cheese or two and make a salad to serve).
Broiled fish is something that also scales up pretty easily, and it frees the stovetop for sides.
I too am time constrained and am often having weeknight guests. The key for me aside from planning ahead (since that's not always possible) is to keep a well stocked pantry (which is tough in my small kitchen, but this can eliminate a mid week shopping trip from time to time).

Sdebrango's Contest winner is a crowd favorite: http://www.food52.com/recipes/13349_flank_steak_on_texas_toast_with_chimichurri

Whether in the sandwich form with a side, I ust made it two datys ago for my sis-in-law and teenage niece with some homemade mashed potatoes. So good. I've made it at least 5x now for 2 -16 people.

Also, chicken scarparello, chicken piccata, and chicken marsala.

I love chicken picata...

And don't forget AntoniaJames' great stew: http://www.food52.com/recipes/11328_west_village_beef_stew

In the colder months, I almost always do a make-ahead main dish like Beef Bourguignonne or one of the beef stews here on food52, or Merrill's truly outstanding Chicken with Sausage, White Wine and Artichokes (which I have also made and served the night of a weeknight dinner party, but had prepped everything else and made dessert the night before). Braises taste better the next day, and are easily made the night before, and people love them, so those tend to be my favorites. In the summer, we grill everything (kebabs, flank steak -- this summer, using pierino's Mysteries of Korea Town and sdebrango's prize winning recipe) and all veggies (zucchini, yellow squash, eggplant and onions) also grilled at the same time. Great question! I'm looking forward to seeing the other answers. ;o)

Thirschfeld's sirloin with horseradish sauce is one of my go-to's:it's quick, incredibly tasty and very impressive to boot! http://www.food52.com/recipes/10783_quick_braised_sirloin_with_horseradish_sauce
It's lovely with mashed potatoes and green beans.

Coming in to fall, I really like this: http://www.food52.com/recipes/7374_caramelized_butternut_squash_wedges_with_a_sage_hazelnut_pesto

It goes well with lots of different proteins.

I love Amanda's braised and spatchcocked chicken:
http://www.food52.com/recipes/8192_spatchcocked_and_braiseroasted_chicken

Also,
http://www.food52.com/recipes/2931_moroccan_style_lamb which is pretty quick to make

Tonight I have to prepare a side for a community TGIF thing so I'm making a porcini risotto "al onda" spiked with truffle oil. But grilled meats are good as long as you can cook outside. You can do a brine or rub a day ahead and hold overnight and then just slap them on the grill.