Monterey is a fantastic place to go whale watching. Discovery Whale Watch has a smaller boat, which makes for a different experience than the boats that can fit 150-200 people. You are closer to the water and have less competition for space at the rail.
I will say that because of the smaller sized boat, you are more likely to get hit with sea spray, and it's definitely more bumpy out on the water. I always take Bonine before going on a boat, and recommend that for anyone prone to seasickness or unsure if they are prone to it. I also recommend dressing in warm layers with a waterproof jacket!
The naturalist, Eric, was terrific. He was very informative about the ecology of Monterey and the wildlife we were hoping to see, and did his very best to find us some whales (we saw a trio of humpbacks).
Highly recommend!