I think we've had this topic before, way back when, but I figure it's worth asking again. Ghost mentioned maybe learning to play bass this summer, so I figured we should expand it into a thread.
I learned to play clarinet in middle school mostly because my mom had played clarinet, so I could use her old one. I knew that was the only way I'd be able to play an instrument, so that's what I picked. I later got to play the school supplied bass clarinet, which was really cool.
But, if I could've picked anything, it would've been drums.
Second choice would be lap guitar.
I also always wanted to learn to play piano, but I know that's a lot harder.
My youngest daughter currently plays Clarinet in band class, but she is also learning how to play snare drum so she can get involved with her school's competing Drum Line.