We kept track of our spend for two relatively recent trips: One to Korea & Japan (2015) and the second to Hong Kong, Vietnam, and Cambodia (2014).
For the Korea & Japan trip, we ended up spending approximately $290CDN/day combined.
For the Hong Kong, Vietnam, and Cambodia trip, we spent approximately $230CDN/day combined.
We generally stayed in budget/modest accommodations with the odd splurge. The cost per day was basically total spend divided by number of days including travel days. Total spend included everything you'd expect including airfare, visas, sim cards, etc but not including souvenirs/shopping and no insurance (as we're covered by work for health and are willing to take the risk on general travel). The trips were both about 3.5 weeks in length with consideration that with a longer trip, the overseas airfare (which is one of the biggest costs) obviously averages out more over the days.
For retirement in a few years, we're targeting approximately $350CDN/day combined. We expect costs will increase as we'll have to buy insurance and likely need/want to travel a bit more comfortably. But, we're also hoping we can reduce costs with longer stays by doing monthly rentals, cooking, etc.