I was thinking last week about previous year's Christmas gifts--which gifts were hits--which were just a waste of money. By far and away the best toy we've ever bought the kids has been Magnatiles. I about choked on the price last year when we bought them (just over $100), but they've been the best investment toy--EVER. They are the most played with toy in the house--by everyone--an almost 8 year old girl, 6 and 4 year old boys and an almost 2 year old girl.
I admit I was a bit underwhelmed (as were the kids) when they first saw the box, but once we opened it up and started playing we quickly saw the potential. I bought them thinking they could help my oldest with spacial dimensions (and they have), but I've been most surprised with my 4 year old. The structures he creates are amazing. They are an awesome "stand alone" toy (he makes a pretty cool Washington monument) , but they've also been made into castles for playmobil people, a train for animals, a zoo--you name it. He's not usually a kid that will play for long chunks of time by himself--but he'll actually go into his room often now to be alone and build.
Even the almost 2 year old enjoys it. She makes "towers" by stacking the tiles flat and her brother is teaching her how to make "ice cream cones." Admittedly her favorite part is probably knocking down the creations of her sister and brothers, but because they can be rebuilt so quickly they usually don't mind too much!
We bought the 100 piece set last year and while it's been enough to make amazing things, with 4 of them playing with it all.the.time we're going to invest in another 100 piece set this Christmas so even more can be built.
So, if you're looking for a nice, sturdy, noiseless, toy that all the kids in your house can enjoy (and then pass down to your grandkids--because there's nothing that can break on them!) I'd recommend Magnatiles.