I'm thoroughly convinced that to appreciate wine at its fullest, your choice of stemware is crucial. The stems you see, smell, and taste wine in has an incredible influence on how you perceive the wine. I'm absolutely convinced. Absolutely.
I've written about stems in the past, but it's an idea worth repeating. You don't need a different glass for each different wine - I don't believe that nonsense for an instant. Material-wise, crystal is a must, for thin rims and a distortion-free bowl. You want to see the shade and sheen of the wine clearly, and thin rims allow the wine to enter the mouth smoothly. Thick glass 'catches' the wine as it rolls into your mouth, and affects palate perception. And of course, shape of the bowl is the most important. You need a tulip shaped bowl, to be able to properly aerate and swirl the wine. Stem length is up to personal preference - I happen to like my stems to be shorter, like these ones, but it's all about how the stem feels in your hand.
Do you need to buy expensive stems? Maybe. It's certainly no coincidence that the best ones are always expensive. Riedel is a safe choice. My wishlist - I'd like a few Zalto Champagne glasses, and a set (or 3) of Ravenscroft Burgundy stems.
Just please...don't buy Ikea.DF