Travel camera

Thanks everyone for all the help. I am leaning more towards the pm2 even though there are people that suggest a better camera. It's small and light for a mirror-less camera and it is cheap. If I can really get just as good pictures with this camera then it seems like an obvious choice to me (maybe I'm wrong?). I would love to get an OMD in the future, but I'm afraid that on the trip I would avoid taking it out at times because I am afraid of damaging it. I figure that I could always sell the pm2 body and then end up with 2 lenses for pretty cheap that would work on the OMD. If I am wrong in these assumptions?

I guss now that I am seeing that all cameras should perform similarly optically, my next concern is lenses (another reason to go pm2 for extra $ for glass). I am thinking that my next purchase should be a nice prime. I am thinking something in the wide to normal fov (14-25mm). This leaves me with a good few lenses to choose from. Size would be nice, but all the pancakes seem to sacrifice somewhere. The 20mm f1.7 looks awesome but still pretty expensive, even for used (what is a good price for one). I have looked somewhat into the sigma 19mm. Would this be a good lens to consider? I know it is big, but it is cheap ($200 new). I don't want a prime for the sake of a prime, but I would like it to offer something that my kit doesn't offer.

One of the avenues of photography I am most excited about trying is long exposures. I looked at the filter size of the olympus 14-42mm kit lens and can't find a 9 or 10 stop that will fit. If I get one of the primes, most of them are 46mm and I could find a few options (is the B+W a good filter?).

Thanks again,

Tim