Yep - if you're looking at moorage in the PNW, marinas advertise open or covered - open is open to the sky, covered is most often covered by a roof, but not enclosed. If a boathouse you will see that advertised separately as a house or shed.
You will also see slips advertised as single or double. A single slip will have finger piers on both sides of your boat (and thus be a bit more expensive) where a double slip you share the slipway with another boat and only have a finger pier on one side of your boat. I think most marinas around are set up with double slips as they are a more efficient use of the marina space, but you do see single slips from time to time....Everett built a few large ones in their new north basin. If they aren't specifically advertised as single you can generally assume they are a double configuration. This gives rise to being flexible - especially when just getting into a marina - of docking on either side, or in either direction, since you might get a bow in - port or starboard tie as your first available slip.
A side tie will usually be along a long pier that doesn't have any finger piers, or along one side of a pier that can't have them - due to space at the edge of the marina for example.
An end tie will be at the end of the pier. or dock...