We've got 3 Echo Dots scattered around the house. Like someone said earlier "Play X on the Whole House Group" (you gotta set up an audio group in the app) lets you play music everywhere. I'll usually throw on ESPN Radio or whatever in the morning so I can listen to Dan LeBatard while I'm putzing around. It's good for holidays and parties, especially if you have a Spotify account since it's integrated and you don't have to say "Alexa, play Wu Tang Clan...on SPOTIFY" every time. Just "Alexa, Play Wu Tang Clan" will start up a playlist.
You can say "Alexa, Guard Mode" and it'll listen for glass breaking, smoke alarms, etc. And then notify you via text. Handy if you're away from the house.
You can make calls through it if you're into that. Also you can set it to find your phone. It'll call it and turn your ringer to loud.
If you've got multiple ones you can talk from room to room. Just "Alexa connect to Family Room" from my bedroom and I can ask for something and can talk in real time.
We get into stupid wars with "Alexa, Announce" and then say weird shit that it broadcasts in your voice around to every device. Or just tell everyone it's dinnertime.
You can set up routines. Buy some cheap Chinese smart bulbs and start throwing them in lights around the house. We've got 3 outside, then Family Room, Play Room, Office. When we go on vacation we set them to go on and off at pre-set times or you can just say "Alexa, Away Mode" and it'll randomize all the lights in the house while you're gone.
Works with my TV, end of the night it's usually "Alexa, shut it down" and the TV turns off and all the lights inside that are on turn off. It'll open Hulu, Netflix, Prime, etc on the TV if you ask her to.
Weather checks are used pretty much daily, usually "Is it going to rain soon" and she'll tell you the exact time rain is expected if there is any. Sometimes you want some random fact and just ask her instead of using your phone. Timers are good, it'll keep multiple named timers going so like "Alexa start a pasta timer for 8 minutes" and then another for something else.