Always an interesting topic
I've wrestled with this very same question many times myself.
And in the end It has always come down to the type of traveling I will be doing. Most (90%) of my own personal travel is for the purpose of taking photographs, so what gear to bring is always a question. But the longer I shoot, the more I come to realize that less really is more.
I'm usually on foot at all my locations, there is no better way to really immerse yourself into the place and open up a lot of opportunities for photos. And as strange as it sounds (at least for me) the more "prepared" I am, the less I enjoy the trip.
What I mean by "prepared" is having the full range of focal lengths and apertures needed to cover all possible situations. For example, with the 5D I used to travel with the following: 17-40L, 24-105L, 50/1.4, 70-200/2.8 L IS, and a tilt-shift thrown in for good measure. But just because I was carrying all that gear, I didn't necessarily take better pictures.
I never realized it until on one trip to Western japan I forced myself to trim my gear list down to a 5D with mounted 24-105 f4 L IS, plus a 50/1.8 in my pocket along with a couple of spare batteries and memory cards in another pocket. What made this drastic change in gear possible for me was the fact that I was traveling with a friend who also shot Canon and they had decided to go the sherpa route and take a whole slew of lenses covering all focal lengths. So I figured I could borrow a longer lens if I happened to need it for a particular shot.
Over the entire 4 day trip, I only felt like I "needed" a longer focal length once. (Much to my surprise) But on the flip side, I was constantly enjoying the lightness of my rig. The 24-105 stayed on the camera most of the day, unless I needed some really shallow depth of field, and at night, I would go out with just the 50 attached to the 5D.
This was not anywhere near as limiting a I thought it was going to be.
I still do wrestle with what gear to bring on a trip. I seem to start out with a lightweight kit, but as the days go by I plan more, and more, and the kit grows. But then usually right at the last minute my sanity returns and I trim it back down to more reasonable proportions.
Your mileage may vary of course depending on your shooting style, and the location of your travel, but I suggest you "bite the bullet" once to see how it tastes.
And as a crutch, you can still bring he whole usual kit along, just leave it locked up at th hotel for a day and go out with a minimal set of gear and see how it goes. That way if it is not to your taste you can slip back into what works best for you.
