most used is definately my 24-70, if i shot less events and more wildlife (my passion then it would be the 70-200 with my teleconverter)

24-70 f:2.8 all the way!!!
You are into portraits and you will LOVE this lens!
I bought it and can't go without it!
I recently bought the 70-200 cause I had to rent it all the times for the horse shows, but the 24-70 came one year earlier in my life

Best thing to do!
That is how I made up my mind on all the lenses available!!!

yeah renting both would be best
if i HAD to choose to have 1 lens only it would be really tough, i love EVERYTHING about the 70-200, and it suites my passion, however the 24-70 makes me money so guess that would be the wiser choice
some people are against shooting portraits with anything less than 85mm, but many are now changing (as long as composition is ok and you possition the subject near the centre so they dont suffer from lens distortion)
you seem to shoot your portraits outdoors most the time, so its easier and better to shoot long
if you were indoors more then the 24-70 would be better for the tight spaces

its not easy to "tell" you which lens to get but i thnk the 70-200 would suite you better
alternatively the 24-70 and 135 f2 would be an awesome combo for you

Honestly, I find it easier to just do an all-round thing. I find sometimes I don't have enough room behind me to back up and take a picture... I'm always in a too small of a space (my house is small). The focus isn't all that great, I don't know if there's something wrong with mine or it's just made cheap (so I've heard). I just don't favor it all that much... honestly, can't remember the last time I used it. It's cool for bokeh and portraits.. but pff, you know who I am, landscape :). So using the 50mm is like... why? lol. It's not as wide, either. The one MotherofTwo is mentioning (24-70) is ultimately the next lens purchase I get, nothing else, just because it's so all-round. I should have got this as my first purchase. I use my sigma whenever I have the chance, it's my favourite so far.

I would choose the 24-70 for portraits because then you don't have to be like 80 feet away from the people (like the 70-200) Just think about being on max zoom-in with the 24-70 all the time (zoomed in at 70). That's what you would have to go through using the 70-200... always having to be quite a distance from your subject for it to focus, cause you can't be too close. Although the 70-200 makes a neat perspective with the background/foreground part when you are zoomed in from a distance. GAH! It's just preference, really. I had to be quite a ways from my nephews using my 70-200. I don't know if it's just more work, or something to get used to... but that's my small experience from it. But I also don't do much portraits

Perhaps renting (like mentioned earlier) wouldn't be a bad idea to see how you feel about them!