How much cash (Euros) should we take to Spain for 11-day trip in April?

Start out with about 200 euros small bills only.
Use your credit card for everything. Nowadays most merchants only take cards everywhere. Only use cash as needed. You won't need to use much. If you happen to run out of cash use only ATM attached to a bank during open hours. Put you money in a neck wallet under your clothes with your passport.Do not put your wallet in a bag or pocket. Otherwise you could get pickpocketed easily especially in Barcelona

Actually, if you’re considering bringing the cash with you from home, getting euros from your bank before you leave for Spain, you’ll pay a higher exchange rate than if you wait until you’ve reached Spain. Use a debit card to pull €200 from an ATM after you’ve arrived, then get more later, if needed. The difference you’d lose on a couple hundred euro transaction may not be enormous, but you’d still come out ahead using ATM’s in Spain, rather than giving more of your money to your bank.

We’ve been here 13 days and have used about 300 € but we’ve used cash for things we could have easily used a card. But as said, there is no point bringing euros with you. Get them here at a cheaper rate. There’s a cash machine every few blocks.

Cards are accepted in most places and cash is accepted everywhere. Last May we didn’t come across any shops that were card only, but did run across three that only accepted cash. I’m sure there are some places that only take cards, but we didn’t come across any in the small towns we visited. We used a lot of cash only because we had a lot of Euros remaining from a previous trip. For future trips I’ll only be taking 200-300€ in cash.

@Indyhiker What fees are you paying for withdrawing cash?
I find Barcelona a minefield full of DCC and had a high bank charge the one time I've used a bank ATM in recent years. The 8 euro per withdrawal charge could make getting euros while still in the US competitive. Granted, I avoid using ATMs in Spain now and bring cash from France.
OP, you don't have to worry about tips because people have salaries but service workers will target Americans and say "tip isn't included" hoping you'll cough up €. Not necessary.

Yes, echoing Bets, don't feed the beast!! The service workers are more and more preying on US tourists, knowing that most are too timid to not tip.

To the OP: Get cash at a BANK-RELATED Bankomat when you arrive. You may be offered the option to "get cash in your own currency" or something like that. This is the DCC (Direct currency conversion) and is a huge ripoff. Use a card with no or low fees - we use the Schwab bank card, which charges $0 fees and does not pass bankomat fees to us. I can't recommend them highly enough.

Card-only businesses are not legal in Spain, but most will accept both cash and card. In many, they'll indicate a minimum amount (10eur?) to be able to pay in cash.

Mikel, did you mean to say there's sometimes a 10-euro minimum to pay with a card? I have seen (primarily in Norway/Sweden) places that don't take cash at all, but never a place that took large cash payments but not small ones.

We have been in Spain for five weeks and have only encountered two situations where we could only use cash - a bus in Valencia and one taxi driver in Girona. Everywhere else has been happy to take debit/credit cards.

I’ve been in Madrid, Malaga and a rural part of Andalucia on this trip. I’ve withdrawn money twice and don’t recall any fees being charged. I was expecting some from my last trip to Spain. But I honestly wasn’t paying particular attention to it.

@acraven - I thought Mike meant 10€ to pay with a card too.

I was in Spain for a week last month and never needed cash.

I’m going to Spain for a week at Easter with my Dad and I told him to change up 50E. I’m not not getting any. I’m hoping that should be more than enough cash.

Sorry, I meant "card"...

David,
Obtaining cash via an ATM is simpler than describing the experience in writing. Research where your card works without being charged fees and you should be able to google the locations. We arrive without pre-purchase of euros and all works out. We prefer bank sponsored ATM's, but use a variety of locations (if possible we walk a few blocks away from tourist zones as additional measure to insure NOT using an ATM programmed with higher fees). Cashless has become a prevailing form of payment and suggest you do read up on avoiding Dynamic Cash Conversion offered in many tourist areas. Often a mobile card reader will be brought to you to process payment. If you are asked to select DCC please be sure and decline then CHECK to insure the option was not accidentally added PRIOR to you signing the bill or hitting the approval key.
We choose to leave cash tips, maximum would be 10 % and commonly 5%, on the table to avoid marking up the credit charge. We believe there is a rise in expectation of tipping within tourist zones and have found the pre-programmed question of "Do you want to leave a tip? with auto select percentages" more common. Most of Europe pays a Living Wage so tipping is not a vital element of their income. Forthrightly we find eating out in non-tourist areas to be less expensive and more enjoyable without the request for tips or DCC.
Strongly encourage asking for print out of all your charge card receipts and keep to compare with monthly bill. We rarely find an issue, but like the assurance of double checking the bills.