911 vs. GTS
I agree with almost everything stated here. I owned a 2007 911 Turbo, 6 Speed, and 2008 GT. Here are some of my personal experiences. Again, though, repeating much of what was stated above.
I had my greatest drive from Los Angeles to San Diego one day in the GT. It was my greatest grand touring experience ever. At the time, I also had a 2006 Coupe, and I would take the Coupe out to do canyon runs - very fun. It was much lighter and more nimble than the GT. I also had the 911 Turbo at the time. I had some of my greatest canyon runs in the 911 turbo. When I put that car into "sport" mode, I felt like I was part of the car, that the car was an extension of my body, not like any other car. And the thrust of that car, 0-60 in under 4.0 seconds, was in a different planet compared to the Coupe and GT. (And the 2010 911 Turbo with PDK is in the low 3.0s and Turbo S at like 2.8 or 2.9!) I took the GT out on canyon runs - it was "okay", not at all like the Coupe, and not anywhere near the 911. The GT was just too heavy - I have the same issues with my SL 55 AMG - it's just too heavy and at some point, the laws of physics take over not matter how good the suspension.
I had to give up all three of those cars, and a bunch of others (550 Maranello, 360 Spider, Gallardo, to name a few).
If it means anything, hanging on my wall at work for me to day dream and keep working hard are pictures of the following cars: 911 GT3 in black with grey rims and red calipers, 911 Turbo with PDK in metallic dark blue and red calipers, Gransport in blue and red calipers, and GTS MC Sportline in white with black interior and white stitching and black calipers. If I had the money, I'd get them all! But for now, I can only get one, and it likely will be the Gransport, given my lack of funds and what I can afford right now.
But if you can only have one, then, like one of the persons already said, think long and hard about what you want in a car and what you want to get out of it. Make your decision on which one is going to satisfy the more important aspects of what you want.
Hope this, along with the other posts, helps.