chicken satay skewers are a good side for pad thai.

I like those served on a big bed of Spinach, fresh or lightly warmed up in the pan to soften. A side of noodles, quinoa or couscous can also do if you want something else than rice.

A salad with a dressing that will complement the stir-fry flavors -- spicy peanut, miso, rice-vinegar... Or a version of that popular potluck dish "Chinese chicken salad" -- the one with the napa cabbage and soy-flavored dressing. Broken ramen noodles optional.

Grilled chicken or meat that has been dressed in a soy marinade. You could grill earlier and keep warm.

Fruit or fruit salad.

If you are worried guests will leave hungry you can offer a heavier dessert such as cheesecake.

You're right, stir frying more than 1 dish (and for more than 2-3 people) is hard work. Luckily, there is a lot of variety in Chinese cuisine. If I'm feeding a crowd, I sometimes make, for example, roast belly pork, boiled Hainanese chicken, steamed chicken with shiitake and wood ear fungus, steamed whole fish with ginger and scallions (also good en papillote in the oven), or braised soya chicken. Chinese greens such as bok choi, gai lan or choi sum are delicious steamed (the advantage being you can make a larger quantity in one go), then dressed with sesame oil, a sprinkle of Maldon salt flakes, some sesame seeds and chili flakes. I'm sure all of the ingredients for these dishes will be described in Grace Young's book, and I highly recommend Fushia Dunlop's books and blog for techniques other than stir frying.

Cold noodle dishes could be a good option

Although not traditional for a Chinese meal, I also like to serve salad (a mix of greens, sprouts, julienned veg, whatever you like)l, tossed with a soy, mirin and ponzu dressing.

Brothy soup or dumplings would be excellent, if you really need multiple courses. I tend to think of stir fry (at home anyway) as more of a 1 or 2 pot meal, so my first thought would just be to double the recipe.

I agree with previous commenters, cold (or just not piping hot) noodles, particularly those just tossed with sesame oil and sliced scallions.

I like to have steamed edamame in the shell as an appetizer, and fresh spring rolls with thai chili dipping sauce on the side. The spring rolls can definitely be made in advance.

ill second steamed edamame. You can make them feel a little fancier for guests by making gomasio to go ontop instead of just plain salt. Gomasio is a combo of toasted sesame seeds and course salt ground together. Just google for a recipe for the right proportions, I usually use the one posted on martha stewart.
Maybe even another steamed veggies (something really fresh and in season so its flavor stands on its own). You can dress them up a little too, say toast some sesame and have a bunch of green beans trimmed and ready ahead of time. Get the a pot with a steaming basket set up and start to heat it. Just throw them in the steamer before dinner is ready and pop them out, toss with some sesame oil and soy sauce and then throw on a serving dish and sprinkle with toasted sesame seeds.

This isn't a side dish, but I like chow mein noodles as an alternative to rice.

Abbie, I'm thrilled you're enjoying Sky's Edge and stir-frying several times a week. I love all the suggestions you got. As the weather gets colder you might want to make a soup like Hot and Sour or a Egg Drop soup which can be done ahead. My mom always paired stir-fries with braised dishes. There are lots of wonderful braises but a few of my favorites are my mom's Rock Sugar Ginger Chicken and Lemon Chicken (the recipes are in Wisdom of the Chinese Kitchen). They're super easy and delicious.

Stir fry is sort of an all-in-one dish. With just some rice, you've got a complete, round meal. So from a nutritional standpoint, I don't think you have to worry.

But from a fun dinner party standpoint, Asian appetizers are fun.

Pot stickers or eggrolls could be fried in advance and then reheated in the oven while you work the wok. Lettuce wraps would add some crisp freshness. Spicy edamame always get devoured. Simple veggie sushi (sweet potato, avocado, asparagus...) can be made in advance. Tempura, fish or crab cakes, miso soup, satays... when in doubt, just think of things that are fun to dip in sauces (peanut, sweet chili, hot mustard...).

If you enjoy cooking Chinese food, then you might be interested in Fuchsia Dunlop's latest book, Every Grain of Rice: Simple Chinese Home Cooking (not sure if it's out in the US yet). This is Chinese comfort food, with the emphasis on vegetables, and sparing use of meat. Like her earlier books, this one demystifies Chinese ingredients and techniques; it has useful suggestions for substitutions if particular ingredients are hard to find; and it includes typical menus, or combinations of dishes for 2, 4, and 6 people. I think these recipes would complement your stir fry dishes very well.

Thanks for the great ideas, everyone! And the cookbook recommendations.

I like that idea!