Measure out and reserve 10 ounces wine. Divide remaining wine between 2 ice cube trays and freeze until firm, about 2 hours (frozen wine cubes can be frozen in a zipper-lock bag for up to 2 months).
To a blender, and in this order, add the reserved 10 ounces wine, simple syrup, strawberries, peaches, and frozen wine cubes. Blend until smooth, scraping down the sides of the jar as necessary. Pour into chilled wine glasses and garnish with strawberries.
Rosé wine: Or substitute sauvignon blanc, pinot Grigio, or riesling. Avoid white zinfandel which is too sweet.
Simple syrup: Combine equal parts sugar and water together over medium-low heat in a saucepan. Stir until just dissolved, then cool before using. I tried this without the simple syrup and it tasted too sour, in my opinion. But if you insist, you can reduce/omit the sugar or substitute Splenda, honey, or maple syrup to taste.
Blender order: Just like with a fruit smoothie, you need to add the liquids FIRST, then the solids, then the ice, as a LAST ingredient.
Make ahead: Freeze the wine into cubes and store them in a ziplock bag for up to 2 months in advance.
Rum. Add a shot or two of rum (or vodka) to the blender to kick things up a notch and make it a tiny bit more alcoholic.
Peach schnapps. Get some extra peach flavor with a shot of schnapps or peach liqueur.
Sparkling water. Lighten the drink up by adding a splash of seltzer water.