I love peppermint vanilla and use vanilla FO for that. There is no true vanilla EO, but for more "natural" vanilla scents, you can use vanilla oleoresin, or benzoin.
I also LOVE Spearmint, Lemon, and just a hint of Tea Tree. The lemon tends to fade a lot quicker (top note) but if you can add a little more EO than you normally do then this mixture is golden!!