I get a 24 bottle case of Mexican coke (0.3L bottles), and then once every couple months a six-pack (0.5L bottle size) of Dr. Pepper if it's on sale. The 24 case lasts me 4-6 months, and the six pack will last about two months. If I have two cokes a week, I feel like my teeth are going to fall out lol. I used to only drink the coke with rum for Cuba Libres, but now I have one by itself (no booze) once in a while so I have soda a little more often. Before that, I'd drink soda so infrequently that my stomach would feel a little off for a bit if I had one.
Normally I drink mostly water or unsweetened iced tea, or now since we're going into winter, hot tea, plain.