Go to a decent wine store and ask the expert. I finally learned about white wines a little over a year ago, and it opened by eyes. While a Riesling will possibly fit what you're looking to buy, different regions and cultivations can yield vastly different tastes from a Riesling -- from dry to very sweet. Ditto for Gewurtz, which tends toward the sweeter, but I actually have a lighter, drier Gewurtz sitting in my kitchen right now.
Don't forget the white wines out of Alsace, which are spectacular. You could try looking for a Tokay Gris from Alsace, if there's a decent wine merchant with a good selection. For best results, stick to French wines labeled "Grand Cru". For the white wines of Alsace, the prices aren't that bad, and the quality is excellent.