I think I just like saying the name of this toy!
One of my favorite AIG teachers (thanks Diane) recommended this game. She uses it with her before and after school kids and said they loved them. I think it looks like a great mulit-age toy and would be easy to take along on trips or store at your house. It has high reviews and there is even some cool you tube videos with instructions and structures you can make with them. They have several different sets: butterflies, under the sea, and just regular octagons.
The toy is sold by Hearthsong and I love lots of the toys on this website (check out the fairy homes if you have a girl).