It's been awhile since I've been on here, but I saw this thread and I had to post. 993 all the way. After buying my 86 911, I am liking it more and more each day. I know many people with 996s (Turbos, GT2, GT3, etc). They all look the same as the Boxster inside. One of the guys that goes on drives with us just traded his 996 Turbo for his old 993 Turbo. Much more of a driving experience with the 993.
The 996 will provide less worry free driving for a little bit, but eventually it will be old too. The 993 will hold it's value. They both are going to cost money to maintain. Just be glad you're not paying $15k for a clutch in a Ferrari 360 after 5000 miles.
I'm thinking about upgrading (again) and looking for a 993 Turbo or a 997S cab. If I did the 997, I would drop the Boxster. If I did the 993, I would drop the 86 911.
Either way you can't go wrong (993 or 996), but the 993 will be a better investment both in $$$ and in
-David