Thanks everyone. I was thinking about the butternut squash/couscous recipe. I made it for a party a few months ago, in Tokyo, and everyone loved it. I should have mentioned, this party is at work. At little like the office -- festive cheer, but no corporate budget. Potluck for lunch. I'll let you know how it goes. Thanks!

I've made this one several times to rave reviews. It's colors are perfect for the season.
http://allrecipes.com/Recipe/Marinated-Broccoli/Detail.aspx

You could do a Panzanella - Tuscan bread salad - one of those dishes everyone does slightly differently, but the classic components are largely red/green - tomatoes, cucumber, basil... you can vary it to taste (add red bell pepper, anchovy, onion, capers, etc.) Delicious and served at room temp. Here's Lidia's version: http://www.saveur.com/article/Recipes/Panzanella-Bread-and-Tomato-Salad ...and Marcella Hazan's: http://www.cooking.com/recipes-and-more/recipes/Panzanella-recipe-4651.aspx ...and Ina Garten's: http://www.foodnetwork.com/recipes/ina-garten/panzanella-recipe/index.html

Also the roasted cauliflower gremolata on this site - I brought that to a party and it was great at room temperature http://www.food52.com/recipes/7015_roasted_cauliflower_with_gremolata_bread_crumbs

Shaved Brussels sprout salad? Lots of ideas on the food52 site: http://www.food52.com/recipes/search?recipe_search=brussels+sprout+salad

Or to be different, maybe a Spanish tortilla dish. Travels well, can be served hot, room temp or cold. http://www.food52.com/recipes/search?recipe_search=spanish+tortilla

Or frittata: http://www.food52.com/recipes/search?recipe_search=frittata

My very favorite Christmas side dish--no cooking, no reheating, no refrigerations and it's red and green and white and gold: bite-size pieces of cauliflower and broccoli and cherry/grape and/or yellow pear tomatoes tossed gently with a vinaigrette of fresh lemon juice, light olive oil, oregano or dill, red pepper flakes, a splash of water, coarse salt, cracked pepper and a teeny bit of sugar. (I won't tell if you use a bottle of Italian dressing instead.)

How about http://www.food52.com/recipes/2538_fregola_sarda_with_caramelized_squash_and_charmoula or http://www.food52.com/recipes/7374_caramelized_butternut_squash_wedges_with_a_sage_hazelnut_pesto or http://www.epicurious.com/recipes/food/views/Roasted-Vegetables-with-Pecan-Gremolata-236485