It really depends on your style.
We eat very lite in the world, no one seems to want to give any time to eating so we do a lot more snacking than anything else. 5 of us spend anywhere from 50-100 a day. We always breakfast in the room (thank goodness for Pop tarts!) and never buy drinks (water is always free if you ask). We go to WDL at least once a year (used to live in SoCal and had AP's for 8 years). In WDW it was about the same.
If you go to the second post in the "Everything you want to know about vouchers" thread there is a link to menus and prices for WDW. Serving size is average-large imho.
Other expenses always kill us as my DH and I both have a weakness for Disney stuff (and so do our kids, go figure). We try to limit each person in our group to $25 at DL, since we only go to DW every few years, and there is more to buy, we budget over $100 each for those trips.... so we spend more on 'things' than food!