I spent a month in Ecuador last September, also lived there for several years in the past, so do have some current information about money there (haven't been to Peru in quite a few years, however, so don't know the situation there now). Anyway, for Ecuador:
* As someone noted, Ecuador is 'dollarized' now, so no foreign transaction fees.
* Most ATMs do charge a fee for withdrawing funds, which as I recall was typically $6, regardless of the amount withdrawn (so if you are going to use a high fee card, take out larger rather than smaller amounts). Every once in a while I'd hit an ATM that didn't charge anything, but don't remember if it was always the same bank -- it definitely was the exception not the rule. To avoid fees altogether, I used my Schwab Bank debit card at ATMs, since they reimburse all ATM fees without question (also foreign transaction fees, if needed).
* Many businesses in mid-large sized Ecuadorian towns take credit cards, even for smaller more dive-y hotels. A chip card was never required, and I don't even remember seeing chip machines in most places, but that might be changing.
* Among credit cards, I'm not sure how common it is for Discover to be accepted. Like their deal in China, Discover has a relationship with Diners, which traditionally was one of the most common credit cards in Ecuador - but honestly I don't recall seeing/hearing that Discover is used very much (maybe I just wasn't tuned in to it....). I personally used both CapOne (Visa) and a Barclaycard (MC) no foreign transaction fee cards (the latter giving double points for all travel-related expenses (e.g., hotels)). Never had a problem with either being accepted. On the off chance that you get extra points on Discover this quarter, why not take it, though -- what have you got to lose?
* Despite diligently notifying Schwab about my travel plans, at least once in every country (developing ones, at least) I end up at problems at some ATM, and have to call the 800 number to verify that it's me. This is very annoying, but I was told by Schwab that it's because there are actually two layers where a withdrawal can be rejected -- one is the Bank who issues the card (in this case Schwab), but the other is the underlying credit card company, i.e., Visa, MC, Amex, etc. Apparently there is an additional action that needs to be taken to make sure the credit company backs off as well (you can't do it directly -- the bank has to do it).
* I didn't have any problems with card skimming or fraud using credit or debit cards in Ecuador, thankfully. No counterfeit bills either.
* I drew from ATMs but also brought a lot of cash with me from the US (most of that was intended to be used primarily in other countries but I still had a bunch left by the time I got to Ecuador). All were clean bills, in multiple denominations. There is a chronic problem of no small change/bills in Ecuador (and a lot of developing countries!), so actually ones and fives are always pretty useful. I had everything from ones to $100s with me.
* Ditto on the advice above about money belts, hiding stashes in various places, and using PacSafe. Ecuador does have a bad problem with robberies, luggage theft, etc., so be vigilant (nothing happened while I was there, traveling all over the country, using public buses, etc., but you never know.).
Hope this helps.
