Poached salmon with yoghurt dill sauce is one of our standards for bringing as our contribution to outdoor summer dinner parties. Asparagus is good on the side. Everybody loves it.
We also use this as our large group Christmas Eve after-church suppers for whoever is lucky enough to be invited to our place for supper around the fireplaces, with the tree (Christmas Eve requires seafood, and you can do this in the afternoon so it's ready when you get home.) One or two of those huge Costco filets, depending on numbers, is good to poach. Easy to do.
Recipe here. We poach the large filets intact and present them on a large tray. It's more appealing that way.