If as previously mentioned you don't want a richly sweet dessert wine, but a medium sweet white, look in supermarkets for anything German described as Spatlese or Auslese, the latter sweeter than the former. If you are willing to spend �6-�8 or so, you can get a very nice bottle.
Also, German whites are very clean tasting and are generally lower in alcohol than other wines, both of which attributes lessen the likelihood of a hangover.
If you do want the richer style, Sauternes is definitely the one to go for, but it is generally dearer. Spanish Moscatel de Valencia is a cheaper option, widely available, often described as liquid marmalade.