For the last 2 years, ive been using a 17-40L for my walkaround and studio lens, however, at times i feel its not enough at the long end for portraits unless you get borderline, uncomfortably close to your subjects. So, ive thought about trading it up for a 24-105L. I had thought about a 24-70L, but there again, i still have a feeling its not going to be long enough at the telephoto end...especially as a main walk around lens. F2.8 really is not a big deal to me either as i rarely have a need for it and if i find myself needing a faster shutter speed, ill just dial in some more ISO.
Anywho, just looking for some opinions from anyone that uses a 24-105L in the studio...are you happy with it? Do you feel you would have been better served by the 24-70?