I've been playing the piano for 10 years now (I'm pretty sure anyway) and since glockenspiels, marimbas, and xylophones are just about the same except with mallets, those three and all instruments that are just about the same (those three are just the first three that come to mind) are very easy to play. I can also play the ocarina rather well. (I taught myself how to play it since I wanted to play Zelda songs on the correct instrument.) I'm also planning on taking guitar lessons soon (as soon as I get a guitar anyway).