I shoot more weddings than anything, and though I do not own the 24-70ii, I rented it for a wedding a couple of weeks ago just to try it out. This lens was prenominal, and was used for more pics than the 17-40, 35L, 50L, or 70-200ii, however, it was primarily used on my crop frame 60D rather than the 5Dii. This may just be my style, but the big tele came in handy more often for my ff. My 2c, rent one or both and try them out. I also rented the 50L, and was not deeply impressed, and though I may buy it eventually, I am not as excited to buy it as I was previously.
If you would rather buy before you try then the 24-70ii is one of the best lenses I have ever used, and I think you will be very happy with it for your events. I would sell anything you can reasonably justify.