Unless you're making a drink where the flavor of Champagne really matters (like the Classic Champagne Cocktail), generally, inexpensive alternatives such as Cava, Sekt, Prosecco or California sparkling wine work well.
Always pour the mixers in first, then top off with champagne to avoid fizzy overflow.
Mimosa
This one's a brunch classic. Increase the flavor by using a ratio of 1 part freshly squeezed orange juice to 5 parts champagne. Then add a splash of triple sec.
Kir Royale
The fancy cousin to the made-with-white-wine Kir, the Kir Royale consists of a dash of creme de cassis (currant syrup), topped off with champagne.
Bellini
Invented at Harry's Bar in Venice, the Bellini is best when made with ripe peaches. If peaches aren't in season, try creme de peche (peach syrup). Use a ratio of 1 part syrup to 4 parts Prosecco.
Black Velvet
This is an easy and strangely delicious drink with a ratio of 1 part black Irish stout to 4 parts champagne.
Death in the Afternoon
This drink was traditionally made from absinthe, in a ratio of 1 part absinthe to 10 parts champagne, but you can probably substitute pastis or another anise-flavored liqueur.
Poinsettia
For a holiday brunch, make Poinsettias: 1 part Triple Sec and 4 parts champagne, with a splash of cranberry juice added for color.
Nelson's Blood
Named for the British admiral George Nelson, this makes a great, if slightly morbid-sounding, party drink. The recipe calls for a ratio of 1 part tawny Port to 5 parts champagne.
Classic Champagne Cocktail
Soak a sugar cube in bitters, drop it into a flute, fill the flute with champagne and garnish with a twist of lemon. This classic drink dates back to at least the mid-19th century.
French 75
There are a number of French 75 recipes floating around; the only thing people agree on is that it's a serious drink with serious ramifications. Here's the classic: a splash of simple syrup, a bigger splash of lemon juice and an even bigger splash (about an ounce) of gin, topped off with a glassful of champagne.
