As the poster above me said, it's really up to you.
For us, we like lower end resorts, so we stay at Pop. It's like our home resort. If we decided to splurge, we'll go to one of the All Star resorts or (if we're feeling like spending a lot of money) the Coronado. But for us, the room is really only to sleep and shower other than a mid-day (2ish-5ish) break.
We don't usually do the dining plan, but we try and pick a nice sit down to do 1-2 times per trip. For our food, we buy a $25 Disney Gift Card every pay check. We each get paid 2x per month, so we can buy $100 in gift cards each month. Then we use that to buy food, snacks, etc. although we like to bring snacks in our luggage.
As far as buying stuff, we try to each buy a shirt every trip. Other than that, maybe buy something for the kitchen or home and that's about it. We might buy 6 items between us on our trip.
So with all that in mind, I know I'm going to have to budget about $3k-$4k for a trip of 5-6 days.