What sort of cake do you think is best to be doused with simple syrup? Sponge cakes? Butter cakes? Also, at what point to you add the simple syrup?

I have used it in sponge and butter cake. Some people do it while the cake is warm, others do it when is cold. The amount of syrup depends on how wet you like the cake. Rum Cake it's soaked in it. But if you are doing tiers, is best to go easy on the syrup
Edna

this is a weird question i also have. I bought a lot of book about cake decorating and most of them have their own cake recipe, all different and most all of them use the syrup right before icing. I have read several posts here on cc saying that you dont really need the syrup. let me know if you find a good answer. Im still a little confused myself.

I use syrups all the time. I got the idea from a book by Peggy porschen. I have used them on the Wasc recipes....haven't tried it on sponge. I brush them one day before I am planning on filling them.

I brush each layer....top, bottom and side to side and then wrap them with Saran wrap over night that way the syrup can infuse into the cake. The recipe I use is 1 cup water to 1 1/4 cup sugar and bring to a boil. Let cool before u apply on cake. U can add liquors, zests, or extracts once cool...teaspoon at a time.

I love using syrups....make my cakes super moist and yummy, especially on white/vanilla cakes

hope this helps