I can't believe no one's mentioned tea. I still drink coffee, but I've replaced my second cup of the day with a pot of green tea, and I'm really into it! For one, it lasts longer than a cup of coffee. And it's warming in the cold months, and refreshing in the hot months.
I like strong caffeinated beverages so I like coffee unless it's yerba mate or something but I LOVEEEEE non caffeinated herbal teas a couple hours before bed.
On that note, I recently discovered valerian root herbal tea (don't laugh (ok, laugh), but I like the one called "Nighty Night Extra"), and it gives me the warm drowzy fuzzies in my stomach.
I love an herbal tea at the end of the day SO MUCH. Sometimes I'll be at a house party, and looking forward to going home and drinking my tea