Growing up in a musical family introduced me to so many wonderful opportunities. From singing and playing the violin to directing a teen swing choir, the musical foundation my parents gave me has brought so much joy to me and, now, to my kids that it's immeasurable.
One of my earliest musical experiences is playing with the Rhythm Band Instrument Set my parents purchased, probably before I was even born. That same set lasted through all the years of banging and shaking my sister, brother, and I imposed and continued to entertain our own kids decades later.
When I began looking for some instruments for my kids, I looked for the same brand I grew up with and I haven't been sorry. Rhythm Band makes a number of sets (some that come with CDs), all high quality, durable, and really fun. I gladly recommend any of their products; I have not yet found one that wasn't up to our standards.
A few years ago, while perusing the music racks at a local music store, I came across a great innovation. Bookwhackers are lightweight plastic tubing. Each tube is a different color and different length. When you whack you hand (or, in the case of my choir, someone else's head) with the tube, it plays a specific musical note. It's great fun—and great musical training—to play a piece by whacking. If you get the original diatonic set and the chromatic set (which includes the five additional sharps/flats in the scale), you can play any piece you choose.
I don't leave this set in the playroom, as they aren't durable enough to withstand serious sword fighting. But I get them out periodically and they are always a hit with young kids up to adults. And, as per my toy-buying requirements, the set is expandable. You can get extensions to go higher or lower, there are holders, games, and even an accessory that turns the tubes into a xylophone-like instrument.
Give your children the gift of music and it will benefit them their whole lives.