I often stand to play, but have never found a strap to be necessary.

Since this thread is pretty old, I'd like to recommend a Snark chromatic tuner. I've found they grab the note more quickly and have a clear screen display and a choice between vibration and microphone. My red one cost me about $12 Canadian. Unlike the Intellitouch, which had difficulty grabbing the low notes, (I had to tune the low E on my guitar using harmonics with my Intellitouch) the Snark has no difficulties with those lower notes.