Went to Monterey with out of town guests - all kids - they were riveted for 3.5 hours. Need I say more.
In case you want more - The Jellies are the best ever -and went to the "Jelly experience" which I would have taken a pass on , but our french guest insisted - very fun. Also love the seahorses - and the splash zone where the kids get to touch stuff is a favorite as well.
We live in the Bay Area and try to get to the Aquarium every 2-3 years. never disappoints.