Me too. I miss my youthful metabolism.

For the past couple of years, I've been grooving on Ramune, that Japanese drink in the glass bottles with the marble. It's just sugar-water; the flavorings are mild, there's no caffeine, and it's pretty sweet, but it's fun and tastes good. My Cub Foods carries it in the "foreign" section, and I'll get a bottle a couple of times a year. It's the only sweetened soda I drink.

We do drink a fair amount of soda water; just plain, unsweetened, unflavored carbonated water, but I don't think that counts towards OP's question. Gerolsteiner, mostly, but also non-mineral ... Gerolsteiner has a taste, being mineral water, which I like but not so much with meals.