OK, I have the 24-105 (haven't used it and may sell it for something else like a 24-70 ii) I also have the 35L, the 85 1.8, the 100 L macro 2.8, the 70-200 F4L. My EF-S lenses for my T4i are the 17-55 2.8 and the 10-22 Wide.
Thinking of the 50 1.2 or upgrading the 1.8 to the 1.2. Not sure I can justify the 85 upgrade, as the 1.8 is pretty sweet. Leaning toward the 50. I love my T4i and 35L combo, so on my new 5D3, the 50 will be close.
Or, do I stick with what I have since using a combo of my ASP-C and FF with current lenses, covers most focal lengths.
If it helps, I am an event photographer, I shoot models and families too. Looking to get into weddings and have already been asked to shoot 2 in 2013.
You may want to read this first section of my review on fast primes. The 50L is a love or hate lens IMO.