Hi Peter
Yes, we did see the Aurora - quite a surreal experience!
From memory, all the local tour guides have some kind of tracker, that is updated by their weather centre, so that they know when there is likely to be a display and where the best viewing point will be. Our guide postponed our night tour a couple of times because the skies were cloudy and he knew we would see nothing.
It wasn't looking good for the thrid night either and then we suddenly got advised that we would be leaving in 30 minutes! We were taken to a golf course outside Reykjavik at around midnight and spent around 2-3 hours looking up! (Take a woolly hat and scarf or a face covering snood because it will be several degrees below.... ) Cue very stiff necks the following morning!
The lights are milky to the naked eye but when viewed through a lense, you will see the colours that all the photos show. The local legend is that the Aurora, which seem to 'dance' in the sky, are Odin's Valkyrie, coming to earth to guide the souls of dead warriors to Valhalla. Good luck - I hope you get to see as many 'maidens' as we did!
All the best
MLB