I find that I don't always detect vibrations on my phone in my pocket.
Although, really, I don't have it on vibrate because I forget to set it. Maybe it's because my only friends are phone spammers, so I don't expect it to ring.
My ringtone is a song that sounds more like a built-in ringtone at the start anyway and the phone will go to voicemail before it identifiably becomes a song. I get to have a ringtone I clearly recognize without feeling that people will think I'm trying to advertise my musical taste.