My early morning coffee fallback solution for when fresh brewed coffee is not available where I slept, is a single-serving coffee singles "tube" dissolved in one of my four .5 liter (16 oz) bottles of water. Take a nearly full bottle of water, add a tube of coffee, shake and drink. Alternatively, allow it to "steep" for a bit before drinking, for fuller flavor. I usually start off with a supply of Starbucks single serving tubes I brought from home.
Once those initial tubes are gone, I just buy Nescafe singles in any tienda or supermercado along the way. They are readily available, in boxes of 10 tubes.
Just be careful that you buy tubes (sobres) and not tea-bag (bolsas) like coffee servings. The tea-bag format does not work well in a water bottle and requires hot water in a cup to brew. This defeats the purpose of using the tubes, "on the go."
That first caffeine "jolt" albeit served at room temperature, is typically enough to get me to the first cafe down the path, where I can get the first of several proper cups of brewed coffee. Coffee in Spain is typically served in a small, expresso-sized cup. As I like to say, it ain't much...but it is ALL coffee.
For larger, North American-style coffee servings, simply ask for "Cafe Americano." The proprietor will dilute your expresso-sized shot in a larger cup or mug with hot water. That is exactly what they do in Starbucks...
For those who do NOT know, "cafe con leche" means coffee with milk. For those of us who cannot take milk in or coffee (goes RIGHT through me...oops TMI...sorry), simply ask for "cafe solo" which means coffee alone, or black coffee.
If they ask "con azucar," they are asking if you desire sugar in our coffee.
I hope this helps...bottoms up!