I've heard lots of great things about Hoppies too. I'm in San Luis Obispo but haven't had a chance to eat there... But if you have enough time during your visit try Taco Temple. They have a very small place in Cayucous and a bigger place in Morro Bay.. The food is really really wonderful.. Blackened fish tacos, scallop burritos, mango salsa, huge deserts.. just really good stuff.. yum yum yum...
I ate at Hoppe's in September and enjoyed a pretty spectacular meal. I'm notoriously bad at remembering what I ate or how to describe it, so forgive me. Also, I was one in a party of four vegetarians, so I can't help out with any meat/fish-type suggestions. They also have an excellent wine list, which is part of the reason I've forgotten the meal. :-) Definitely check it out.
There's a place on your right just before you walk onto the pier. Cash only. Great fish and chips, a great red fish chowder and, believe it or not, a great hamburger.
And if your're in town overnight the Old Cayucos Saloon is a fun place to drink and listen to live music.
I wish I was there now.