I don't drink wine and my husband doesn't either. So a wine gift would be something we'd end up putting out for the guests, when actually the idea of a hostess gift is that it's something the hostess and host enjoy on their own later....Go beyond the wine idea because everyone gives that.
I have been given really good coffee and that was welcome since guests know we are coffee lovers. We also liked a gift of assorted very nice cookies (like you get at a good bakery, not in a box from a shelf). I would avoid giving mixes unless you know the hosts are very likely to use them.
Please, no fat scented candles either unless you know for SURE that your hosts love them-- especially scented ones that would give some folks a headache! But I do love the idea of nice unscented taper candles for the holidays like peppermint-striped ones I've been given in the past.
We did get one candle gift we still love. Our friend was really into making his own candles and made a pair of terrific clear candles in wine glasses that had a frosted winter tree design on them, so the light shines through the design. They cost him next to nothing to make, I know, but are invaluable to us because he put his time into them. If you aren't into making stuff, that's just fine! Seek out something a bit unusual like that.