Green Boa I haven't travelled outside of Europe since getting the Revolut card so I don't know how useful it will be in Asia. 

BTW no-one is saying don't budget. They're saying don't do busy work for the sake of it. If it will add useful information that you can't get by simple searches then great. I've found my method gives me everything I need and the price of hotels and food from my trip to Seville was no use at all in planning my trip to Brussels. 

Do what makes you feel comfortable but know why you are doing it.

Green Boa It depends what you want out of it. I want to relax on holiday and my only real concern is that my total vacation spend is less than the amount I have budgeted. That's not to say that I don't retrospectively look at how much I spent on hotels, transport, etc but that's only really of value if you're going to the same or a similar country again. How much you paid for backpacker hotels in Vietnam is not relevant to a similar trip to Australia for example. And even if we do get back to Australia next year hotel prices from 2014 are less relevant than a google search.

If you're not heavily reliant on cash, then I find you can get most of the information you require from the payee particularly if you review the information while it's fresh in my mind and enter it into the memo field. Even with cash you can get close enough. The memo field option lets you put hotel or #hotel and then search for that later. Sadly, YNAB doesn't support tags so you need to make sure you're consistent with the descriptors you use. 

If you want more detail and you'll keep the budget entry up when you're on the trip then you absolutely could record more. I personally don't like lots of vacation sub-categories in my main budget because they don't add information that I find useful enough to make it worthwhile. I can honestly say that in all my years of YNABbing I've never needed that information retrospectively. I could see the benefit of them if you're trying to work out in advance how much you need to budget to make the trip viable. It's up to you whether that's in a separate budget or a category group in your main budget. You also have the choice of whether you use temporary categories to ringfence the money and them collapse it into a single category once the trip is over. Whichever option you go for, I'd recommend that you budget in your home currency (euros I think you said) and use a ball park currency conversion rate for the initial data entry into YNAB. 3 budgets in 3 different currencies seems like overkill to me.

Like dakinemaui  said I'd really think about what you want the budgets to do.

• Do you just want to work out how much you need to save up before you go? 
• Will you use it to make spending decisions while you are travelling before you spend?
• Do you want to retrospectively analyse how much was spend on hotels, food, transportation to facilitate future trip planning (assuming this trip has any relevance on the next)?
• How tight is your budget going to be?

That will let you make a sensible decision between the various options and avoid busy work for busy's sake. 

Actually, having peeled back the advancing years and remembered some backpacking trips on incredibly tight budgets I suppose I could see the merit for 3 temporary budgets in Baht, Ringgit and Dong (substitute appropriate currencies obviously).  My backpacking trips were before YNAB but I had always read the Lonely Planet - yes, read and carried the physical books it was that long ago - worked out roughly what I needed to live on each day and, therefore, the type of accommodation I could afford to sleep in etc. I used to keep a very simply running log in a notebook of how much cash I had at the end of each day, how much I'd taken out, etc and there's no reason you couldn't use a new YNAB budget to do that instead. I'd still countenance against making this too detailed. Is the information helping your decision making or not? If not, spend the time getting another beer and socialising?
 

The important bit long-term is how you record it in your main budget and you will have some doubling up to do particularly for card spending.

Green Boa Given you want to track where your money is going on the trip, I'd recommend you make notes of it in the memo section of the transaction.

(1) For credit card use - enter each transaction on its own (in Euros), put the actual payee, and then in the memo section, note what the foreign currency amount and spending is, for example, "1000 baht - dinner." Then remember to go back and fix the actual Euro amount once you have a chance to look at your credit card statement.

(2) For cash use - as I explain above, do a transfer in YNAB, and then do a single transaction for the exact withdrawn amount (in Euros). Then, each time you make a purchase in cash, go back into that same transaction in YNAB and add a note in the memo section. For example, your note may be "500 baht - taxi" and then later in the day, you may add right under it, "750 baht - lunch," and then the next day you may go and add, "1300 baht - afternoon at beach." That way, when you are done with your time in Thailand (for example), you will have a single transaction in YNAB with a list of exactly how you spent the local currency in the notes. And then, when you go to the Philippines (for example), and withdrawn money in pesos, you do another single transaction and repeat the process.