The flight-tag lanyard has been a favourite of mine for a long time. When you're aimlessly digging around your pocket, there's plenty of material for your hand to find quickly, but it's still lightweight enough not to be a nuisance. I attach the ring to the fabric end, leaving the clip free to hang on my bag, belt loop, etc.
The only thing that could possibly make this more useful is a bottle-opener. Just saying.