Besides Extended Horizons both Tiny Bubbles or Scuba Mike should guide both those dives. If you go with a guide, they'll have tanks but specify you need one - once with another operator our guide just drove up in his car and introduced himself - only had his tank. (we had ours)
If not, you can get tanks at Maui Dive Shop in Kahana Gateway or Lahaina Divers in downtown Lahaina - there's other options also, just two I know of. Tiny Bubbles must have gear rental also, they're in the Embassy Suites in Ka'anapali as well.
The Molokini boats all leave from the Kihei boat ramp so they're all about the same in terms of size/amenities (small) so they can be pulled out daily. I wouldn't take my pregnant wife on one of them - there's not a lot of amenities - being smaller boats they pitch more also. B&B Scuba's new boat is probably the most stable, I haven't been on it.
Look into the big powered snorkel catamarans that leave from Ma'alea - they have amenities for getting snorkelers in/out easier. And they feed you lunch. I'm sure the concierge books them - they advertise island wide. Since your wife is pregnant, the
drop at the end of the waterslide might not be a good idea. Pride of Maui is one option - they drop stairs actually deeper
into the water on arrival so it's easy to get in/out. Pride also offers Scuba - I've done it. And Snuba if your wife is allowed to do that.
PRIDE OF MAUI | Molokini Discovery Snorkeling Tour
Where you're staying, you might want to think about diving locally also. We've stayed just up the beach from the Four Seasons and one of my favorite dives is Wailea Point which I believe your resort is either on or borders. The next big resort north of yours is the Grand Wailea - I'm pretty sure they still have an on-site dive operator - if not Shaka Divers or Maui Dreams Dive Co. both do guided shore dives in that general area - Makena Landing or Five Caves being popular sites about 1/2 mi. south of your resort. The next beach south past the point is Polo, north is Ulua. All good dives listed here:
Scuba Shore Diving Site Listing for: Maui, Hawaiian Islands
I like Wailea Beach personally. Around the point there's some lava ledges and we've seen the most interesting stuff there. Once a whole family of cornetfish, always puffers, there's an endemic trigger in the bay and other divers told us they swam with a Manta out there one morning. Supposed to be small wreck out there also but we never found it. Polo Beach I've been told is even better - have not dove there.