Ferrari 250GT SWB or Aston Martin DB4 GT Zagato are the initial two that come to mind, followed closely by my ideal build of my own TR8. Other than that, I'm also a big fan of the older Bugatti's. Especially the Type 35's.
Nial, less than 20 miles from my doorstep is a world class Bugatti Restoration shop. This shop does the work on Jay Leno's Bugatti's as his in house mechanics are usually to busy to work on them. The last time I was there, two type 35's were in house (one was Jay's), there was also a couple of Delehaye's and a Voisin as well. They did the blue Atlantic that won Pebble Beach a few years ago as well. Seen the engines in pieces being preped for assembly too. Very interesting stuff to see.