If you're not a tea fan, you probably haven't tried many of the wonderful teas that exist. White tea, supposedly the healthiest one, has a great taste. I like the plain one, but there are also really nice mixes with all sorts of tasty things.
I also like green tea, with lemon.
Btw, tea also contains caffeine but much less than coffee. Especially the green and white versions contain very little caffeine. Probably not enough to cause any sleeping problems. In fact, they're quite relaxing. And great to sip on and enjoy.
There's also green tea with mint, which is one of my favorites. It's nice and fresh.
And tea is healthy, so it's a great option. Just try out different ones. There's a wide range of tastes and probably there will be at least one you do like.
Other than tea, a cup of warm milk could be an option. It is said to help you sleep well and for me that's certainly too. I do recommend low/no fat milk to limit unnecessary fat intake. And I personally like warm milk with aniseed (the cubes) a lot.
You can add flavors to plain water too. You can squeeze a fresh lemon and add some of its juice to the water. Works for both warm and cold water, whichever you like best.
One other thing you could try is homemade smoothies. You can even add vegetables in them if you like.
Regarding stevia, I have no idea.
