At my wits end-Which lens would you choose for the Sony a700?

I think the 700 is a full frame sensor, is that right? If so, the 50 would not be the best portrait lens. It works in some scenes, but generally you want a 85 to 135. I favor a 85. Even if its not full frame I think I would take the Tamron 28-75 2.8 its a great sharp lens and will give you more options. I would suggest getting the Sigma 50 1.4 later though as its much better than Sony's version from what I have heard and I know the Sigma did great on a Nikon I tried it on when I shot with it.