Vanilla reminds me of visiting my nana while she is baking up a storm in the kitchen. A friend of mind says that she gets a headache when Vanilla is burned but I believe thats when the fragrance is a cheapy.
I light a candle daily to give thanks to the creator - usually a white unfragranced one....but having said that I always have some fragranced ones burning through the house.
Lemon or orange ..usually a citrus base is very good for concentration and focus while working.
Thanks Oliver for your comments :o)