I was in Paris in December, brought one lens with me and that was the 24-105. The weight was excellent, good zoom range. But the only problem I had, it was very dark and cloudy when I went. I wish I had the 2.8 lens to get more light. I found that the 24-105 worked well with good light or flash. Also a contributing factor was my camera iso capabilities were not that great. But I made do.
From reading a lot of reviews of the 24-70II, I would get it, its something that will be with you a longtime with no regrets in a general zoom lens. Only the price will hurt at the moment, but when you see those pictures, you will hopefully say it was worth it.
At this moment, I'm saving up for the 24-70II.
Here is one with the 24-105: