Zooloretto

Zooloretto is one of my favourite family games and it's very simple to play. It is based on the popular Coloretto card game, but adds a theme (which works pretty well): building a zoo. At the start of each round, there is an empty wagon for each player and on their turn players can either draw a random tile (which may feature an animal, a stand or money) and place it on any wagon or they may take one of the wagons. Animals are placed in the zoo enclosures (only one type per enclosure) or in the barn, stands are placed next to enclosures and money is used for special actions such as buying zoo extensions or buying animals from opponents' barns. The game has some really cute features such as fertile pairs in the same enclosure producing babies (a free animal for your zoo). At the end of the game, animals in enclosures and stands score positive points, animals in the barn score negative points.

The components are high quality. Not quite indestructible, but they're not going to be ripped to shreds within 10 minutes.
The rules are well explained and the rulebook also contains a brief description of each animal.
It's great for kids - they get to build their own zoo with their favourite animals. 9/10
It's great for adults - should I take that wagon with the single money tile now? or hope something better comes up later? 7/10
The rules are easy to learn and the possible actions are not complex, but they are varied enough that there is almost always something you can do on your turn to improve your position.
It plays in less than an hour.
(One word of caution. The official two-player game is not very rewarding for adults as you will probably both fill your zoo optimally and the game will result in a draw.)

This game is a lot of fun and the theme will definitely appeal to families. Plus, as the winner of the "Spiel des Jahres" (Game of the Year) 2007, there is sure to be a steady stream of spin-offs and expansions.