For a less intense thyme flavour, omit thyme from the sugar syrup and add it to the lemon juice instead. Make sure you crunch the leaves in your hand to release their flavor.
Add gin for an alcoholic twist.
Tip: Freeze some of the mixture in ice trays the first time you make it so that the next time you have it, you can use these ice cubs in the cocktail so that they won't dilute the flavor as they melt. —madlovefood
Test Kitchen Notes
Honestly, this one surprised me. I just didn't think there was much to it, but there's something about the combination of vanilla and thyme that brings out the best in both. It's a sweet syrup, to be sure, but not without tartness, and the vanilla somehow "organizes" the overall flavor. There's only a touch of thyme to it, and I personally would keep the thyme in the cooling syrup rather than straining it out right away, but overall this is a very pleasing base for lemonade. —mitschlag