I back up my phone to iTunes. In fact it's the only thing that I use iTunes for, I don't use it to sync or manage music or content, thanks to it displaying a dialog box (every time I try) saying that it will erase my iphone if I try to sync any music or content. So I just use it for a full backup of the phone. The backup button works even when I have turned off the syncing features.

I believe that it may be possible to do that same full backup process via WiFi, though I do all my backups wired. Not sure about automatic settings; I do it by manually selecting the "backup" button, but there may be automatic options.

There are sites on the internet which say that AnyTrans will back up your iPhone via WiFi. Though I might use those kinds of products (third party sync products) for uploading songs to my iPhone, I'm not sure I would trust them will full backup/restore or not. Keep in mind that the most important part of backing up is that the restore process needs to be reliable. Since iTunes backup and restore features are designed and tested by the people that made the phone, I feel like I can trust that one. I'm not sure about any others.