Wow, did you deliberately pick three different drivetrain configurations? Boxster S = RWD, mid engine, flat-6. S2000 = RWD, front engine (longitudinal), inline-4. R32 = AWD, front engine (transverse), VR6, i.e., a narrow angle V-6 using a single "siamesed" cylinder head for both banks of cylinders.
If you need to carry more than two people or plan to use your vehicle for skiing/snowboarding trips, then the R32 is the way to go. However, keep in mind that, with only 240 hp, you will get your doors blown off by STi and Evo drivers. I see the R32 as being more of a "gentleman's" STi or Evo, more akin to the Legacy GT Spec. B, a performance sedan with some civility. However, you won't have the reliability of the Japanese manufacturers, as VW's had some quality/reliability issues with both their German and Mexican made products. BTW, I believe its replacement, the R36, will be here soon.
Now for the 2-seater convertibles. The Boxster S will be more expensive to purchase and maintain than the S2000. It likely won't be as reliable, but it will have the Porsche cachet, especially over the more pedestrian regular Boxster. The larger 3.2l or 3.0l flat-6 puts out approximately 40-50 more hp than the base model Boxster's 2.7l or 2.5l, depending on model year. Access to the engine is PITA though.
The S2000 is a performance bargain. It's only short-coming is a lack of torque, especially low end torque. The 240 hp 2.0 or 2.2l inline-4, depending on year, makes most of its modest peak torque output at above 4,000 rpm, so you have to rev it to extract maximum acceleration. It is a sweet revving motor w/ an 8K redline, so there really isn't any penalty associated with getting max performance out of it. Just don't expect the effortless punch-and-go low-end torque of the R32 or Boxster though.
Hope this helps. If I had to choose, I'd go w/ the S2000 or the Boxster. Let poseurs who are too cool to be seen in a Subie drive R32s.
