Yes, I've been advised about Deception Pass at slack only...
If I was at Coronet Bay, or anywhere else for that matter with overnight moorage at dock or buoy, that would be my preference. I'm trying to get a sense as to how feasible a quick detour and anchoring for the night would be.... Like many things it doesn't seem to be as easy and simple as one would hope....
There are options, and you're wise to think them through before you need them.
To over-simplify, I'd say that there are many friendly docks available if it's windy, and many spots to anchor if it's not windy. There are also the buoys.
How big is your boat, if I may ask? The buoys, which are somewhat suspect, would be perfectly fine if you boat is under 30ft. My friend that dragged one aground was in a catalina 400 (40 ft) and in 25+kts of wind.
Grabbing a buoy on Hope Island would be my preference if you boat is small. The island is a neat spot to explore and you're right at the doorstep of Deception Pass and ready to untie and go though at slack.
Alternately the buoys or dock at Penn Cove allow you a nice detour in town but you're quite a bit further from the pass. Langley marina is also a short walk from town. Oak Harbor is less scenic and there is not much to walk to at Cornet Bay.