There are many, many sizes of wine glasses available but average entertainers such as you and I can probably make do with three or four basic sizes.
Wonderful Whites
There are many different shaped white-wine glasses to take account of various subtleties between varieties, but a good-quality basic glass will suffice for most of us. Oxidisation is important for fuller-flavoured wines so people who often drink these may prefer a glass with a wider top. Those who like lighter styles should select a glass with a smaller mouth.
Red Alert
Bordeaux and burgundies ought to be served in large glasses with a round, wide bowl allowing oxygen to interact with the wine and improve its flavour. But, once again, they taste perfectly good in standard red-wine glasses.
Cheers to Champagne
A champagne glass or flute will generally have a long stem and a narrow bowl. This keeps the bubbles in and lets the aroma hit your nose in a most satisfactory way.
Hot Tip: Always hold a Champagne glass by the stem to keep the contents from warming up in your hand.