1. Should I rent glassware or buy it?
For parties of 20 people or more, renting makes sense. It will cost up to $1 per stem or so, and there’s no cleanup involved. Contact a party rental company (they’re listed in the Yellow Pages). If you throw frequent parties, buying glasses may be a better bet. Crate & Barrel’s Viv line runs $3.95 a stem (crateandbarrel.com).
2. Can I use one glass for red wine, white wine, water and Champagne
Yes, for three of the four. The Riedel Vinum series Chianti/Zinfandel glass ($44 for two; williams-sonoma.com) is high-quality stemware that works very well for both red and white wines and can serve as a water glass, too. For Champagne, Robert Mondavi by Waterford flutes ($50 for two; waterford.com) feel especially nice in the hand.