How long does a good bottle of wine last once opened?

It will last opened maybe 3-5 days. You can find at your wine store a vacuum device. You place a cork on the wine and pump out the extra air inside the bottle. It should help it last for maybe a solid week. Its the best solution if your going to recork your wine.

From experience i'd say 3 days after that throw it out..I know It's pretty sad, but u can always buy a vacuum wine saver...i bought one of those and it works great...and your wine will be good for about 4 weeks and still taste like you've just opened the bottle.

A few days. Maybe see if you can find what you like in those little bottles so you only have to open the ones you drink then.

The only thing I have to add is that if you have the fortune to have a very old bottle of wine (probably setting you back thousands of dollars), you may need to consume it within an hour or less after opening it before it goes downhill.

Yup, I agree with the responses of 3-5 days above. I would give it four days to spoil completely.. best to drink it as soon as it's opened. It spoils quickly because of the oxygen that you've let into the bottle (oxidation and heat are wine's worst enemies.) Refrigeration will help but it won't help a lot because the other enemy, oxygen, is still in the bottle.. but throw it in the fridge anyway (corked, of course) to eliminate the heat factor and to slow the oxidation process due to the lower temperatures. Another thing you might want to try is pouring the leftover wine into a smaller bottle if you have one lying around (cleaned out and dried off of course,) this way the wine can be filled to or near the top and sealed (cork, other types of bottle caps, etc..) this will also help prevent oxidation from occurring since the wine isn't exposed to air. Regardless of what method you use, removing the air from the bottle, transferring the wine to a smaller bottle, refrigeration - it should be consumed ASAP (preferrably the day you open it) to ensure that you get the maximum quality out of your wine, and the most bang for your buck.. because once you reach (max) 3-4 days, it's pretty much kaput.

I agree with all other answers, no more than a week, but if it is older try this. Take an Ice cube tray and fill it with the remaining wine, freeze it, and use the frozen cubes for cooking. I put one in my stir fry's, works great

You should look for half bottles. I know of a few wineries that produce splits. Carmen Reserve - Cabernet Sauvignon, 2002 is a nice Chilean red and it comes in a half bottle. Dolcetto D'Alba - Prunotto is a very good Italian red also in a half. As well J.Lohr Mondavi, and many more produce small bottles of nice wines.

3 days is probably the max, and you definitely should recork and refrigerate white wines, however those who tell you to refrigerate all wine after it opens are incorrect, red wines (like merlots) should be left at room temperature (obviously with the cork back in)