I'm glad to know I am not the only one who does not add it all up sometimes!
I tend to take road trips, and stay at inexpensive hotels (unless they are provided by someone's business trip...), or else I do Priceline bidding. I'd use $100 a night for lodging. We would probably camp several nights, so a more expensive place averages in.
We eat breakfast from supplies on hand. Mostly from home, but we'd buy fruit and yogurt on the way. Lunch and dinner about $30 a day per person, rounded up. So I'd allot $200 a day for all of us.
Attractions? I don't mind spending on these if they are recommended. I'm much more likely to spend on the experiences we share together than on the room or food which for us is quickly forgotten. We might buy theater tickets, park passes, museum entry, hop on hop off bus fare (depending on if we've been there before). This could easily be $50 per person on a single day, but on average more like $25 per person for the entire trip, or $125 a day.
Airfares and rental cars really drain the budget. For airfares, I use expedia mainly and do a lot of obsessive checking and rechecking dates and nearby airports. We usually get domestic tickets for around $300 apiece. We use carryon only to avoid the luggage charge, no matter how lovely it would be not to haul that bag.
We have had good luck reserving subcompact cars and getting free upgrades to midsize, but that is just a matter of chance. I am still looking for deals on rental cars when I have a regular visit to one of the relatives. I haven't tried priceline for airfare lately, or rental cars ever. Gas is expensive, but we don't tend to drive long distances every day.
So my family budget is more like $600 a day.
It would be less if we camped every night, or stay in a home exchange. On a camping vacation we'd have less cost in attractions (but still not zero). We would have lower food costs, but not that much since we'd likely buy nice local fish to cook, etc.
We also might visit family, thus dropping the lodging and food dollar cost. But you do PAY for that experience one way or another!