learn to play an instrument

I’ve always wanted to learn to play an instrument. But the question is what instrument? I travel a lot so I’d like something I can take with me on my travels so the piano is out of question. Even a guitar looks a bit too bulky. But then those two are probably the ones that are the most versatile, in the sense that you can always find some music that you can play on a guitar or a piano. I’m not sure it is true of other instruments. On the other hand, I am a complete novice so I don’t know.

What about a flute or some other type of wind instrument? It’s quite small and can be taken everywhere easily. But then, would that limit the music I can play?

Then there’s the harmonica but I don’t know if I want to look like Charles Bronson in Once Upon A Time In The West.

And then there’s drums. It looks like the ideal way to relieve tension at the end of a long day at work but it’s hardly transportable. But if you’re good enough, you can do like one busker I saw in the London tube the other day: drum and juggle with the drumsticks at the same time, without losing a beat! Not that I’d ever manage to reach that level!

And then there’s the inevitable question: how difficult is it to learn to play one instrument or another? Is the guitar more difficult than the piano? Does it matter?

If anyone can shed light on all this, I’d be very grateful.