This is where an understanding of the OSI model is useful: the different types of encryptions happen at different layers of communication.
WiFi encryption protects all communication from your device from the local network (i.e. your coffee shop's network), but not anything past the local network (i.e. the rest of the Internet). WiFi encryption is 'optional', but set up by the WiFi network (not optional as a user).
SSL encryption protects the individual connections you make with the individual destinations (i.e. connections to websites). This also protects specific communication from your device from the local network, but it also protects it all the way to the destination (some exceptions apply).
Here's the problem: you do not always have control over what connections are being sent out by your device. Without the local network protections (i.e. WiFi encryption) you expose all of that to anyone listening.
So, the best idea is to use both the network encryption (Wifi) and SSL encryption wherever possible. You do not have as many options as you think, and you do not have as much control over what is sent out by your device than you think.