- Three Extra Enclosures - this is 3 two-space pens specific to zebra, flamingo & elephant. They are available for purchase from the center of the board for $2. I'd combine 'em w/the Savings Book and/or the Petting Zoo.
- The Petting Zoo - the OP is right... probably the best simple expansion out there. The trade-off between cash & victory points is really nice.
- Polar Bear/Gorilla - I like these better now that I have 2 of them and it's not simply a crapshoot to see who gets the special power first. I also own King K, which offers a 3rd choice. All of these are single tiles which add a special power to your zoo - they are claimed by finishing your 6 space pen.
- Three Additional Buildings - we used these once & I wasn't overwhelmed by what they did or didn't do. Had to look up the rules on them a number of times.
- The Savings Book - an exercise in delayed gratification... makes money less tight later in the game, which is a good thing when using some of the other expansions.
- Zooloretto XXL - have only played once w/2 players. Adds the ability to "clear" 2 of your complete pens for lower points (ship them off to another zoo) and refill them. I'm not sure the extra time is worth the trade-off... however, the Aquaretto XXL expansion is very cool (included in the same box). I want to try this one some more.
- Zooloretto Exotic - have played twice now and really enjoyed it both times. It makes the end game dynamics very different as players have more tiles to avoid and scoring considerations to worry about.
HAVE NOT PLAYED
- King K - see notes on Polar Bear above
- Building Sites - introduces an element of "take that" to the game that I don't like... probably won't ever use them.
- Mission Cards - Looking forward to trying these... but only good with experienced players.
- The Reindeer - was a Christmas card giveaway postcard... a single tile like the Polar Bear & the Gorilla. You can print a copy from http://www.zooloretto.com.
If I was going to rank the expansions in "need to own" order, here's how I'd go:
- Polar Bear expansion pack (includes the Polar Bear, Petting Zoos, Building Sites, 3 Extra Enclosures & 3 Additional Buildings) - online cost: around $7
- Gorilla expansion pack (includes the Gorilla, Savings Books, Mission Cards & 2 expansions for Aquaretto) - online cost: around $7
- Zooloretto Exotic - online cost: around $19
- Zooloretto XXL - online cost: around $22
- King K & the Reindeer (both giveaway postcards you can print'n'play)
In fact, you can print-n-play most of the small expansions from Michael Schlacht's website, zooloretto.com. I just like having the nice professionally printed pieces for my set.