Remember that at a party you're not catering for yourself, but the event and the guests.
Spend a little bit more than you might do for yourself, and go for wines that people know and love, rather than something obscure that's a personal favourite. There are so many different types of parties, but for wines that please everyone the obvious one is Prosecco. And it's probably the best choice, although I don't massively love it! Prosecco is made in tanks instead of fermented in bottles in the champagne method but its price point is good and the quality level is very high for sparkling wine. It's a safe bet as it's inoffensive, not too alcoholic, and has a certain level of sweetness so anyone will drink it, any time. In fact sparkling wine is the only market in the wine industry that's growing.
"Prosecco is made in tanks instead of fermented in bottles in the champagne method but its price point is good and the quality level is very high for sparkling wine."
While champagne is obviously better quality, it's pricey for a party. But a great tip is to buy Cremant from the Loire valley, which is much better value. It's properly fermented, has a better sense of style and place, and is maybe a pound or two more than Prosecco. Some Cremants are as good as champagne, especially the ones from Burgundy (Cremant de Bourgogne). If you're buying still wine go for large format bottles for a bit of celebratory drama.
"The best 'fun' red wines are from Spain and Portugal because you get much better quality for your money, due to the guaranteed sunshine and low production costs."
Red wine in a magnum feels really special and is way better than a few bottles of cheap Aussie Chardonnay or Pinot Grigio. Go for Azamor wine from Alentejo in Portugal, a favourite at Vinoteca wine bar when I worked there. The best 'fun' red wines are from Spain and Portugal because you get much better quality for your money, due to the guaranteed sunshine and low production costs, and Azamor is incredible quality for the price. You can buy a bottle in shops for under a tenner, and a magnum for under £40.