Perhaps you're struggling with this because you're limiting yourself to mass-market tour operators and packages, which for a diver tend not to be very useful. Even if they happen to offer packages to a place generally known for good diving, the hotel choices they offer are usually not the best choices for a diver due to factors like location, convenience, quality of the on-site dive op, etc. They have other priorities. Do some research, see what dive destinations it's easy/reasonable to get to from Toronto (if that's important), then pick an appropriate place to stay and dive in those places. It's not hard once you get into it. If you accidentally eliminate everyplace, start over.
If you really want someone to do it all for you, there are a number of good dive travel agencies that specialize in this sort of thing. Even if you leave it to a dive travel agent, you still want to do some of your own research to make sure they are pointing you the right direction.
As a relatively new diver, you may discover your favorite evening activity is to sleep. Once you get past that, your new favorite evening activity may be night diving.
If you're stuck on packaged tour operators and not comfortable with booking a land based trip yourself, you may actually find the cruise thing more challenging. Booking the cruise ship dive excursions is easy and stress free, but they have a reputation for being of less quality, shorter dives, not the best sites, and more expensive than doing it on your own. If you decide you want to go your own way to get better prices and diving, you'd have to research each port, figure out if the cruise ship excursion or something else makes more sense there, possibly figure out how you're getting there, and worry about getting back on time.
The Curacao Marriott Beach resort might indeed be a good choice for you. It's a nice place and good compromise of everything.
There are lots of nice places on Grand Cayman, but if you prefer higher end places Sunset house probably won't meet your expectations.