Use to live in Pacific Grove. Beautiful country.
Aquarium is nice, but expensive. We use to have annual passes that includes 2 guest passes that we would loan out. If you happen to know any one living there, wouldn't hurt to ask.
Cannery Row is a tourist trap. Don't eat there, at least on the west end. Chart House on the other end is good. If you want sea food in a formal setting, Fisherman's Wharf has plenty. Fisherman's Grotto is pry the best, but do not go if you have small kids. They have a no strollers sign posted and would pry kick out crying kids. Someone mentioned Phil's, which we always found was worth the drive.
what part of town are you staying in?
Big Sur is a must. Point Lobos is nice, but can get crowded. California state parks charge by the car, so you will see a lot of cars parked on 1 and they walk in. Beaches, I like sand dollar best, but it's a good 1.5 hours south. Pfeiffer is popular and has a cool arch and purple sand.
Garrapata is a popular beach and pretty close to Carmel.
Julia Pfeiffer Burns state park is a must. But again, park on the highway and don't pay the parking fee. Check out the waterfall into the ocean and the remains of an old house.
You will likely see whales and dolphins. I saw them on a daily basis just walking along Monterey Bay. You can take whale watching trips year round. Seals are always on the beach at Ocean View and 1st in PG. Sea Lions always on the floating platform at the wharf. Otters in the kelp bed along the bay or go to the Elkhorn Slough and see the huge raft that's usually there.
Beautiful place. Enjoy!