Usually guide books and websites for the country have that kind of information. Where are you planning on going?
I've look a few guides I found in one local book store here, but that one was more the kind "Im rich and I can afford Michelin guide restaurants". Not the kind of trip Im planning, not the kind of place I would dig.
It really does depend on where you're going. If you were to go to Ireland, you would spend a lot on food, but if you were going to Thailand, you would spend very little.
Im planning to visit England and Wales, but in 2015 only. I'm trying to build a basic sheet of costs (using local inflation to have more a real value) to have an idea of how much I need to save. Since I know it is impossible to make a projection of how much I will expend on food, I was wondering if people more experienced on traveling would give me a general idea of how they plan these costs.
About where you are going to stay, I'm finding difficult to calculate cost/benefit - since I plan to visit more than one city, will be more wise to sleep at every city or make daily train trips (for instance)? But I realized that that was a too generic and broad question. So, never mind it. =P