When I have made white wine sauce at home, I have been unable to replicate the classic 'round' taste, with the 'long' aftertaste. The taste I'm looking for is typical for restaurants serving it with white fish, like cod.  I have a theory that this particular quality has something to do with the preparation of butter, e.g. caramelization.  How do I make restaurant-quality white wine sauce? 
What kind of sauce are you making ? a simple "beurre blanc" ? a gravy (with a roux) or a cream sauce ?   Can you describe the recipe you are using (ingredients, technique) ?  What I do (for beurre blanc):  Cook down the schallots slowly in wine; add a little bit of water and white vinegar, it should not be dry. Use cold unsalted butter cut in small chunks Mix in the butter with a whisk until the butter is well integrated. Pass the mix through (sp) a fine mesh to remove the schallots. Adjust seasonings. ... 