Lentil Pilaf would work well.
Boiled new potatoes.
Roasted asparagus and Caesar salad are my salmon go to sides.
I almost always make this salad when serving salmon:
Try grilling fresh asparagus that have been lightly oiled with evoo and sprinkled with kosher or sea salt and course black pepper. After grilled, sprinkle with fresh lemon zest. A dynamite compliment for most fish dishes!
A potato salad with dill (new potatoes or red potatoes would be nice).
I second the asparagus suggestion! Also, try peas or snap peas. Or, take all three, cook until very soft, then make a purée out of it. I had something like this once at a Swedish restaurant and it's a wonderful salmon pairing!
Try freshly sliced fennel with lemon and extra virgin olive oil. You could also add chunks of oranges salt and pepper. Very refreshing!
Mashed potatoes are good especially if you have a glaze or sauce on the salmon.
I like to do an asian-y marinade on salmon with soy, sake, mirin, ginger, orange, broil the salmon and reduce the marinade. I serve it with red quinoa and the sauce and a very simple green veg like grilled or steamed broccoli or roasted brussels sprouts. For a simple salt and pepper salmon we might do zucchini noodles- just salt the zucchini strips until wilted, rinse, toss with a little lemon zest, olive oil, pepper and fresh herbs.