I had a 1997 993 Cab as a daily driver for a while. It was a great car and made going to work much more fun. When it was done being a DD, I moved over to a '97 993 Turbo. 993s are great.
I have had my Boxster S since 2001. For a DD, I believe the Boxster would be a better car. It is more comfortable, the air conditioner works better and it has a better ride. They are just two very different (& great) cars.
Take a look at the Rennlist 993 forum. There is a lot of great information there;
http://forums.rennlist.com/rennforums/993-forum-58/