For Key West, I used Sub Tropic several years ago and was happy.
However, for the Vandenberg, several dive op's have "jacked the price up" for the Vandenberg trip. They say because it's farther out or other excuses. It's just as far out as the other wrecks and reefs. So several of the shops haven't raised their prices for "vandenberg only trips". No sense supporting a shop that's trying to screw the diver by raising it's prices for the same trip. So choose your shop wisely.
As for what dives.
The Spiegel Grove is great. I've dove it multiple times and see something different each time.
The Duane and Bibb are great dives. Sister ships, but one is on her side, so makes it a different dive. Still good.
The Eagle is a good wreck also. Freighter that is split into to.
The Benwood is a good wreck, but not much of a wreck now as it's falling apart. but 60+ years of coral growth have left it a great site to dive. makes a good "2nd tanker" after the Spiegal Grove as it's sorta on the way back in.
The City of Washington is similar in that it's an old wreck that's falling apart. It's shallow with a large debris field and lots coral heads around it.
Alopholas Busch is a good wreck, further down in the keys.
The other wrecks around Key West didn't excite me as much as the ones in the upper/middle keys.
For Reefs, the popular spots in Key Largo and Molasses reef, French Reef, Christ of the Abyss, etc. some folks like diving Christ of the Abyss, some don't. It's got some HUGE coral heads around it. but it's also shallow and a popular snorkel boat destination also.
several other reefs up and down the keeps and they all have great things to offer.
Islamorada FIsh Company as noted above was a favorite of mine. the food was good, but I mostly liked the atmosphere of sitting on the dock, eating a basket of fish, drinking a cold beer and watching the sun set... it was good and relaxing.
I highly suggest before going picking up Ned DeLoach's (or other guides). Lots of good info in the book about dive sites there.
Amazon.com: Diving Guide to Underwater Florida, 11th Edition (9781878348395): Ned DeLoach: Books