i carry it with me on 90% or more of my trips. great for people shots, and other things. just last week, i was taking pictures of parents giving their kids blessing drinks and statues at a shrine in japan. a few weeks ago it was my daughter's expression while she was experiencing shopping with my wife for the first time in hong kong. one of my favourite ones last year was penguin walking on the beach near capetown.
note that it's only 1 lens in my travel arsenal and it will only be used for a relatively small percentage of shots. i generally bring the (in order of priority
24-70 L, the 85 1.8, a 1.4 teleconv, sigma 15mm fisheye, the 135 L. then depending on what else i'm expecting, i'll add the 80-200, 50 1.8, bigma, and/or possibly a second body. you also have to think about bag weight and its impact on your trip, as well as the pausing to take photos, swap lenses, then take several more. my family is pretty well used to this (finally...) but i do most of my travel on my own.
if you are considering the 24-105, obviously it would cover a decent range. you could combine that with a teleconverter and take it to 147mm. i'd probably find f4 a bit limiting as would not having any primes. what other lenses do you have?