Because I’m quadriparetic, I use echo for everything. Really like it. I use a lot of virtual switches and tie them to either other devices or routines in SmartThings. Smartthings makes echo on hundred times better. 
So among other things:
1) To change modes (“Alexa, turn on party time!”)
Here’s the FAQ on setting up echo to use virtual switches in SmartThings to change modes or just run one of your ST routines.
2) With the SmartThings/Harmony integration, for granular control of my home entertainment devices. Everything from “Alexa, turn on ESPN TV” to “Alexa, turn on pause Netflix” takes a lot of set up, but works very well when SmartThings is working well. Some of these, like the pause, are a little clunky, so more able-bodied people might not use them, but are great for me. The basics like “Alexa, turn on Roku,” are perfect for everybody.
3) To unlock the door from the inside. I have the Kuna video lantern at the front door so I can see who is there. I could have echo unlock the door to let someone in who doesn’t have a door code, like one of my housemate’s friends, without having to physically go let them in, which could take me several minutes.
4) To run a good night routine after I’m in bed, which turns off several lights in the path from the living room to the bedroom, powers on a motion detector operated nightlight, change the mode from night to asleep, turns on an indicator light so my housemates know I have gone to bed, and anything else I might put in the good night routine. ( my own door has in autolock feature so it’s always locked, but if it didn’t I would put lock door in here also.) “Alexa, turn on Good Night.”
5) I also use echo for anything I can trigger from IFTTT. I don’t really want to go into all of that because if you don’t use those other services/devices it might not make a lot of sense. But it’s a very nice feature. I can even send a predefined emergency text to my neighbor this way without needing any other devices. “Alexa, turn on Emergency.” This is also based on a virtual switch. So echo turns on the virtual switch, which I use as the IF in my IFTTT recipe.
My project report is here for anyone interested in costs and equipment details for these specific projects: