Grilled asparagus is great with steak. Get some fresh asparagus, snap about 1/4 of the "fat" end off of them, put them all in a large ziplock bag, add about 2-3 tablespoons of olive oil, shake in a little salt, pepper, and garlic powder, close the bag, shake it up for nice even coverage, and then either throw it on your grill with the steak for about 5-7 minutes(turning once, halfway through), or if you are purely cooking indoors, put the asparagus on a cookie sheet and bake it in the oven at 350 for about 10 minutes.
Alternately, if you REALLY want to go all out, this is fairly time consuming but is the absolute best side dish I've ever made. The handful of time's I've served it, it's all everyone can talk about because its so awesome.
Mini Twice-Baked potatos.
basically you just use any twice-baked potato recipe that you would find online, except that you use the little slightly-larger-than-golf-ball-sized red potatos.
Cut em in half, cook them in the oven with a little oil on them. Ideally, brush the whole potato with olive oil, skin and "cut" side. Place the potatos flat-side down on the cookie sheet, and then sprinkle sea salt on the exposed potato skins that are oiled up. (350 degrees for maybe 25-30 min), then once the potatos are soft, let them cool, use a melon-baller to scoop out the insides into a big bowl.
Once you have all the scooped out potato in a bowl, use any twice baked potato recipe to doctor them up, adding sour cream, butter, milk, cheese, garlic, whatever you want.
Spoon back into potato skin halves, top with cheese & bacon bits, and then put them back in the oven for maybe 10-15 minutes, just long enough to get them hot again and for the cheese to melt.
These are nice because you can do ALL the work days ahead of time and just put them in the fridge, them pop them out and warm them up in the oven and you're gtg.
Then you have little twice-baked potatos that only take like 2 bites to eat, they're almost like finger foods, but you can easily get as many or as few as you want. No one is stuck with 1 giant hulking twiced baked potato if they don't want that much, but you can also eat a million of them if you want a bunch, you aren't done once your 1 potato is gone. You also tend to get a higher ratio of the tasty salted potato skin in each bite. They almost end up tasting like a cross between a twice baked potato and a potato skin appetizer. They are incredible.
