After putting only 13,500 miles on my Continental ContiSport 3 SSR (Self Supporting Runflats) they showed signs of needing replacement (not terrible - but I don't like to get them all the way bald before I replace them).
I didn't like the choice of SSR or the price. I was able to get a better non SSR tire, a full size OEM wheel (front width), and another front tire. For now I am happy with the decision. The right is better, the grip is better, and the tires are lighter (meaning better fuel efficiency, handling, and acceleration / braking).
I am securing the full size spare flat in the trunk and standing it up on its side when I need to transport other items of size (like luggage). I bought a breaker bar, 17mm deep socket wrench, and a torque wrench that I store in the lower compartment in the trunk. I am still hunting for a good portable jack and tire repair kit (plug type, not goo). This is a very recent thing for me (new tires went on today).
I'm sure my next flat will be in the middle of the hood in the pouring rain and I will regret to hell not going with SSR's.
My thread about my decision and searching for some hardware is here:
http://x3.xbimmers.com/forums/showthread.php?t=625427