Best single-malt Scotch...

Glenmorangie, madeira wood finish

Any Islay malt is worth a go if you like peat and smoke, but I echo the earlier recommendations for Laphroaig Lagavulin. Consider also the outstanding Ardbeg and Port Ellen malts (the latter no longer being in production and thus a bit harder to find). As previous posters have indicated, Talisker on Skye is also an excellent dram (and worth a visit if you're in the area).

I'll hafta keep a lookout fer that Port Ellen!

I enojoy the glenrothes, single speyside 1989!

For a warm, rich, taste (perhaps too rich for some) Highland Park is a great choice. Worth a try, IMO. Works great with jazz for me. Cardhu is on the opposite side of the spectrum, very light and "easygoing" yet not dry (perhaps too easygoing, careful, hehe…). All in all an excellent all-around “companion.” Most of the others lay in between, except for those with an exceptionally strong character, like Laphroaig or Talisker, which are definitely worth a try, but may be something of an acquired taste for the non-aficionado.
[slight hijack] I usually prefer my whisky straight, but I was wondering if there is a “golden rule” (other than trial and error) about adding water to your drink? [/slight hijack]