Currency to take with us for Eastern Europe tour

When we took that tour, we spent a couple days in Prague before the tour. I believe we took some Czech money and some Euro (we were ending in Vienna), but for the other countries we visited the ATM upon arrival. The guide was good about explaining where to get the money and suggestions of amount to withdraw.

Czech Republic, Poland, and Hungary aren't eurozone countries. Each has their own currency. You can sometimes find merchants who'll take euros, but would likely lose out as exchange rates get rounded in their favor. You're likely going to just want to estimate how much you take out from an ATM in each country based on how much time you'll spend in each, and what you're looking to spend while there. Taking out too much means getting left with a bunch of extra currency that won't do you much good in the next country (or, again, having to exchange it for less than favorable exchange rates); taking out too little means more visits to ATMs and possibly more ATM fees.

Depending on the cards you use, you may be best off relying on a debit/credit card for most purchases (check foreign transaction fees and such) to minimize how much cash you have to use.

Something I've done when in situations like yours, if staying at hotels, is leaving any local currency I have behind as a tip for housekeeping, and paying some towards my hotel bill at check out (if I have too much to leave behind as a tip).

I recommend only taking an ATM debit card from a bank that charges minimal fees per withdrawal. Then, when you get to each place and you need some cash, you make an ATM withdrawal in the local currency.

There's really no point for buying multiple currencies ahead of time (at a steep price) when you're in each country only for a few days each. You may need a lot less cash than you anticipate.

And if you’re traveling on the ground from country to country to country, you’re not going to face ATM’s at airports being your first opportunity to withdraw local cash, with the potentially worse exchange rates that airport ATM’s can involve. Pull out some cash from an ATM after you’ve crossed the border into each country and you’ll be all set. Maybe get your first Czech koruna during your orientation walk on Day 1? As mentioned above, if you’re using a credit card for many purchases, you might not need tons of cash.

Do not worry about the different currency needed for these countries. When you get to Prague, take out some Czech money for the time you are there prior to the start of the tour. The evening of your first meeting as a group, your tour guide will hand out information about how much is recommended to withdraw in each country. This is what happened when I took the tour and it worked out fine. It's a wonderful tour, enjoy.

RS FAQ tip recommends taking US dollars:
https://www.ricksteves.com/travel-tips/money/cash-tips

Cash and Currency Tips for Europe By Rick Steves

Resist the urge to buy foreign currency before your trip.

What to Bring

US dollars: I carry $100–200 as a backup.

Go to the nearest bankomat and get money in the currency of the country.

WATCH OUT FOR HIGH CONVERSION FEES. If you have the option, DO NOT ACCEPT THE CONVERSION. Let your bank do the conversion.

We are on currency #6.

Like Agnes said, take your debit card and get local cash when you need it. If you can, predict how much cash you will need and withdraw only that much.

Actually, go to the nearest bank owned and operated ATM. It is quite possible that the name "Bankomat" is being used for a privately owned chain of ATM machines, just like "Euronet", which will either demand a high fee or charge a high exchange rate since they are not on the interbank network - or both.

I would bite the bullet and the any leftover cash to a exchange shop and change it to the local currency when you get to the next stop.

You need to pay attention to what you read on the ATM screen to be sure you haven't chosen a bank-owned ATM that charges fees. A lot now do that. And as mentioned above, you do not want to conduct any transactions in dollars, because the bank / hotel / restaurant / store gets to choose the exchange rate, and it will most definitely not be in your favor.