jedovaty- I'd say get another XKR, but maybe I'm just spending too much time around the XKR owners in my Jag club
My wife and I had a pair of the big Benz coupes (W126 560 SECs, one was an AMG car). My wife and I simply *LOVED* them, but they're not getting any newer and the maintenance can be really something. Much as we liked them, once we got the Audis we never really gave them another thought. Glad we had them, but wouldn't buy one now.
IME (and everybody will have their own opinion), a truly vintage Benz is more fun to think about than it is to really drive

so I'd pass on the 280SL (a friend of mine has one for his wife's other car and it just doesn't do it for me). The 300 SEL 6.3 sedans drive *almost* like modern cars, but the maintenance will simply kill you and finding a nice one is tricky.
S5s are nice *IF* the sunroof treatment doesn't bug you. I was surprised to find that it really bugged me. Sorta a pricey ride though.
I don't think the Jetta will do it for you, but that's just a guess. Their R32 or something like that might be more to your liking, but after the Jag...eh..I doubt it.
Interesting situation, wonder what you'll decide to do
