How long can you keep a opened bottle of wine?

[White Wine Lover]

I know WW does not care for the Vac-U-Vin and he is VASTLY more experienced than I, a humble novice, but I want to say (at the risk of getting flamed), that I have had good luck with the Vac-U-Vin. It comes with rubberized stoppers and a gadget that fits on top of the stopper, then you pump the air out of the bottle. Now, maybe it's because I'm a novice & thus my taste is not fully developed, but it seems to keep my leftover wine tasting just fine with little change, for a couple of days. Perhaps the variety makes a difference? I like to sip Pinot Grigio, Chardonnay, or Savignon Blanc.