Take both! Your photos are your most precious memories of your trip.
Just be sure to backup your photos. I know too many people that had an 8GB SD card, and when the camera was lost or stolen, so were the memories.
I traveled Ecuador with the Nikon 18-200 lens a few years back. Awesome pix. First thing I did when I got home was sell it though. The thing was just soooooo heavy that I didn't take as many pix cuz I got sick of carrying it. I switched to a 50mm lens. Lately I'm wishing I just carried the 35mm as the 50mm is just a bit too tight. I've been stitching panoramics together though, so that works well. It's rare I want to get any closer so I don't feel the need for zoom anymore. So I'd try to travel with fewer lenses.
When paired with a smaller camera (I have the S90 and love it, but the photo quality is still waaay below my old D50) my worries about the wrong lens size disappear.
Enjoy!