I recently traveled for two months in the US and Ecuador. I didn't take a phone, and used WiFi whereever I was. Some places didn't have it, but those places didn't have phone coverage either, so I wasn't missing anything (one didn't have electricity). Everywhere else, connectivity was about as good in the US as in Ecuador. Some hotels only had centralised WiFi, and told me my room might be too far away for it to work. It also appeared that places where there were a lot of tourists had some problems at certain times. Maybe because everyone was loading their pictures from their camera onto the cloud as soon as they came back from seeing something. Maybe because EVERYONE was trying to use it, and the server was configured for less devices being attached, especially as people now have several devices each.
I used a device called "My Passport" to put all my photos onto, and this device is also a WiFi hub. As a result, it acted as a repeater, and I was able to access the internet in rooms that didn't have strong signals. I found this very valuable during my travels, not just for the purpose I had originally intended. If I had had more than one WiFi device, I could have also used the "My Passport" to have just one connection to the WiFi supplied at the hotel.