I work for an international mining company and travel a lot. I know it sounds exciting to be a "frequent flyer" but the shine can wear a bit thin after you've been at it for a while.
Because I travel so much, and have had more then one bag disappear, everything that goes with me goes carry-on, so I travel pretty light. About 1/4th of the time I carry only a C***n point n shoot camera. The rest of the time, when I have my K200d, I rarely travel with more then two lenses.
I like "normal" lenses so my first preference is either my F 28 f/2.8, or my FA 35 f/2 since either of them are very nice lenses, very light (under 7 ounces), and both give excellent image quality in the "normal" range. Typically this lens will get 80% of the use. I have thought of carrying my Sigma 18-50 several times, to give myself a wide angle option, but I have never done it and I can't say I've ever missed it. I guess the thought of carrying that extra 12 ounces of weight has stopped me.
My 2nd lens is almost always a long, telephoto zoom. Although I have several choices, over the last few months my usual choice has been my Promaster 80-210 (a Vivitar copy) because it gives good pictures and weighs under 10 ounces. Finally, if it ever breaks I can leave it behind in a hotel waste bucket and not feel too bad about it.
As for a tripod, I have only carried one with me once, and I never used it. I do stabilize my telephoto, but usually by resting it on something handy nearby.
Everyone has their own preferences when it comes to travel, but to me it is more important to have the camera when I need it, not to pack a lot of extras I probably won't need. The K200d and both lenses weigh a bit over 2 pounds. So far this works for me.
This all sounds great but you should be aware that when I'm traveling locally in my car, I have been known to pack and carry way more then I need