Do we need to bring power converters? We have iphones, possible an iPad, a macbook, and go-pro
Not sure origin country. Most USB connectors just need a plug adapter. Most laptops have a converter built in to the cord. Again, just a plug converter.
Coming from the United States.Thank you
You only need a power (voltage) converter if bringing electrical goods that heat up, e.g. hair-dryer, hair-straighteners, iron (other than dual voltage). Electronic goods such as phone chargers, camera chargers, merely need a plug adaptor.
You can check this out with manufacturers' websites directly, as your question concerns YOUR appliances, rather than Spain (cf https://www.apple.com/uk/shop/question/answers/iphone/do-i-need-a-power-converter-to-charge-my-iphone-while-traveling-in-europe-to-convert-voltage-from-220-to110volts-or-do-i-just-use-these-plug-adapters/QU74C22U9FK9FCP2P)
Most good hotels have hair dryers in their bathrooms.
For modern mobile electronics, your original chargers should convert the voltage worldwide. You just need the adapter as qaminari mentioned. If you want to be sure, look on the charger and it should say something like 100 to 240V, 50-60Hz.
If you want to charge multiple phones and tablets, I suggest you invest in a multi-port USB charger. They should cost only a few US$. I have a 4-port one so I just bring one charger and a plug adapter for USB devices. Cameras and laptops are still likely to require their own charger (and additional adapters).