Sonos sound system

I bought one recently. My house is already wired for surround sound so I didn't buy the speakers--just the connect and bridge which I've got hooked up to my receiver. I'm considering buying a speaker that I can use in the front while kids play in the driveway etc.

Any recs on what speaker to get? Are there other speakers (non-Sonos) that can be integrated easily into a Sonoes system? It appears that there is not a rechargable version and that you must be plugged into a power source. Not a deal-breaker but it would be nice to have a battery-powered version.