Originally Posted by Wingman32
Not sure about Denmark, but Estonia is a most definite no. Estonia is not yet in the Euro zone and you will need local currency to get around.
The same thing about Denmark, they have their own currency, Danish crowns (DKK), so I can't see a reason why e.g. a taxi driver would accept euros.
Although it is probably possible to pay with Euro at hotels, in tourist shops, the large department stores and some major restaurants.
But I wouldn't recommend it anyway as the exchange rate is probably really bad.