I agree the $100 US dollars per day per person is a good estimate unless you are planning more TS meals than you suggest in your posting. If multiple trips for coffee QS or an alcoholic drink per day is a given, take that up to $150 per adult. Things that raise costs a lot are fancy coffee drinks, alcohol, and a lot of snacks. For me, the cost of buying a bottle of water or soda definitely add up. I find carrying a reusable water bottle that I refill with cups of free ice water can easily save me $10-$12 per day, and that’s just me. Also, not letting yourselves order more than you can really eat at QS can help. Splitting a meal and adding an extra side, is often enough for two people, especially if snacks are in your future. I was skeptical when folks told me that at first, but after 20 plus trips now, it really is advice to think about. When traveling with my partner, we frequently order one entree and add either an appetizer, a side, or dessert and we are full. And we aren’t small folks…we are both overweight, big eaters!
To keep costs down, consider a grocery delivery order for things like bottled drinks, breakfast food, snacks. I bring some non perishable snacks from home in the suitcase and eating them also gives me extra space for souvenirs. Unless I am planning a TS breakfast, most breakfasts are eaten in the room regardless if it’s a solo trip or family trip for me.
But if you really want a budget, you do have to do it yourself, day by day for each person. Excel is great for this, but paper and pencil will work. I’d set up three meals and three snack/drink purchases per person each day and fill it in. After you do a couple of days, it gets easier because you will understand typical QS pricing better. So, it’s not as overwhelming as it seems once you get started.