Isnt Jungle Island absolutely awful?They have a lemur encounter that shouid be closed down,some roadside zoo-type monkey cages,a poor, dark, reptile house,a pathetic penguin pond,clipped parrots galore(including both Hyacinthine and Blue-throated Macaws).And they obviously have money,just look at the entrance complex..its like a university building.Surprisingly shabby overall.Dont know if you bothered but just down the road from the Seaquarium are the remnants of the old Crandon Park Zoo...at least four or five old sets of cages/aviaries,whether suitable or not ,that was quite a setting for a zoo.
We didn't get the chance to visit Monkey Jungle or the nearby Alligator Farm - Zoo Miami took a lot longer than expected (even then, I'd have preferred an hour or so more in the Wings of Asia aviary

). I actually spent the day with zooman; we had bumped into each other in Animal Kingdom by coincidence and decided to match up a zoo visit later in the week.
I was very surprised by just how poor Jungle Island is. Some absolutely terrible enclosures, and a lot of unpleasant practices. I don't think I'd ever seen a mixed white lion & white tiger enclosure before. There were a lot of repeated species (like common marmosets & lar? gibbons) consistently in poor enclosures - zooman highlighted that this gave the impression of an exotic pet farm.
I don't remember seeing the lemur encounter - perhaps it was too late in the day?
One of the things I absolutely couldn't stand was that at the end of the Jungle Show (featuring 6-month-old tiger cubs, an adult wolf and a gibbon in nappies), a young tiger cub was brought out. It was claimed to be 6 weeks old but frankly I'd be surprised if it was any older than a very generous 21 days. Eyes barely open, and held around for paid photos. On questioning, the handler stated that she was 'the mommy' for all of the cubs at the park, that way they survive, whereas they wouldn't if they were left with tigers. A futile conversation.
There was so much that was wrong with this place. As you say, they obviously have the funds, and it was very busy during our visit at the end of the day. It's hard to understand why it's so amateurish throughout.
Pros: Flamingo pool was a decent size, and the 'tame' cassowary in the parrot show was a highlight (that show was better than expected). Another interesting point was that the signage for white tigers was much more scientific and more informative than I expected.
Unfortunately I didn't make it to the Crandon Park Zoo site. My entire visit to the Seaquarium was quite limited because we had to drive back to Orlando for our afternoon flight back to London. I spent a fair amount of time being denied access to the Orca stadium (as I was unable to stay for the show). I can imagine what an amazing setting for a zoo those Keys are.