bucky... I practice the KISS principle re seafood to be sure I only "enhance" and never "cover-up" the inherent flavors they have... ya know "keep it simple :) .... in Oregon where I grew up, we had a TON of Dungeness Crab too.. so I've cooked/eaten my share of the "tons" of them...
The ONE thing I've noticed over the years, is that most commercial cookers cut way back on the salt they use to boil the crabs... someone said it was a cost-cutting measure, but salt it CHEAP.. so I doubt that...
The jury is still out as to whether the Dungeness Crab should be cooked "uncleaned" or "cleaned"... I've tried them both ways and I'm not sure which I prefer, even now. It's easier to cook them, then clean them... and many claim the flavor is better that way.
They must be boiled in their shell in boiling salt water.. period, nothing else added...between 10-15 minutes depending on the size of your crab, but never over 15 minutes... then cleaned and eaten warm with perhaps melted lemon butter.. or whatever "gourmet" additions some may prefer.. I keep it simple and just use clarified butter as a dip.
If the crab are allowed to cool, they can be "steamed" to heat them up, and then eaten the same as if they just came out of the pot.
For mussels, typically we'll saute in olive oil some diced onion, celery, and plenty of fresh garlic in the pot, then add about a cup of a decent drinkable white wine, toss in the mussels and steam JUST until the shells open,, very important.. they overcook rapidly and can become tough too.
Strain your broth and serve it as a dipping sauce on the side.. some add heavy cream and reduce the sauce (that's good too)... I sometimes thicken the sauce with a chunk of butter... and also serve a maelted "clarified" butter as a second dipping option.
But there are hundreds of preferences... that's just kinda how I usually do it.
"Never order chicken-fried steak in a cafe that doesn't have a jukebox."