It's not terribly illuminating to say, you serve them with a protein of course, and possibly with a veg as well.
Getting down to nuances: Because they're so rich and delicious in themselves, you have to decide whether they're going to be the star on the plate, or a supporting player. For instance, they'd partner equally well with poached halibut, roast chicken, or filet mignon. In any case, I think it's a good idea to use a sauce (e.g., hollandaise, jus, pan-reduction, to bring the protein and potatoes together.
Alternatively, you may want to stick with a simply grilled or roast protein and do something with the veg. Butter glazed carrots with a Pernod and dill finish, for instance; or even creamed spinach.
If you're thinking about using them in a way which really features them, you could use them as an app partnered with a smallish portion of something like moules mariniere.
Getting back to the potatoes: Perfect for a "finishing" salt. Your best, is none too good. Think about tossing in some chopped fresh rosemary at the last minute, and/or "speed-basting" with rosemary or sage added after the potatoes have already started to brown.