I wouldn't bother with using a wall plate in the patio (and I didn't). I just used a rubber grommet in the hole in the patio wall where the speaker wire enters the patio. A wall plate right next to a speaker doesn't look so nice and you will usually not be able to mount the speaker over the plate to hide it, so why bother?
Inside the house is another story and depends on how things are wired. If the wires run from behind your equipment, over the ceiling, and out to the patio you would use a wall plate behind the equipment so that you can connect to the receiver. I've tried a few different types and found I like the plates with binding posts on both sides from PartsExpress. MonoPrice.com has the same thing and is actually a few bucks cheaper.