Let’s start for QR codes – there are 2 issues here, first of all there is not standard pre installed application on the phone which can read them and second even if user has one then it takes time. Or you can ask the question yourself – when last time have you used QR code ?
Now let’s get to Bluetooth beacons (aka. IBeacon) this is even more tempting but as everything what is shiny there must be trap somewhere, and yes there is quite few, first of all phones today don’t have standard app which allows to read beacons, even if will be introduced soon users will have to start getting familiar with it but that will be not very soon. Other issue is that beacons send signal all around the place, that signal bounces all around the exposition area, as result being even very close to the object you might receive signal for other beacon then the one which is closest to you. Last issue is the battery life of beacon, after few months up to a year the battery dies, needs to be replaced, roughly calculation if you have 20 beacons you need to replace battery every 10 days, if you have 200 then every day. What’s worst beacons don’t report battery status to single location so you have to walk around exposition area every so often and intercept signal to find battery status every day. Not mentioning cost of the beacon which is between 20 to 30 USD each.
The bottom line is that good old piece of paper with number works quite well.