You haven't really said what you're trying to prevent. Like you already said, non-https web traffic will be visible on an open wifi: there is literally nothing you can do to prevent this. Most protocols do not contain any encryption and you can't really stop that.
Things like ssh have built in encryption: if you ssh home you can be relatively safe in the knowledge that no one is spying on you, or if they are it is nothing but gibberish.
Or are you worried about someone hacking into your Pandora? No need to worry, stock firmware doesn't have any open ports anymore, so there's nothing for hackers to connect to and exploit, even on an open wifi.
So yeah, the only thing you should really be worried about is sending unencrypted data over a regular http connection, and there isn't much you can do to stop it.