I did one of these tourist helicopter tours of the Grand Canyon and the Vegas strip a few years ago. I'm absolutely terrified of heights; for some reason I'm fine in a plane, but the idea of a helicopter scared me a lot more.
Taking something like Rescue Remedy in advance for a few days (plus being very drunk the night before and only having 2 hour sleep, at most) seemed to help calm my nerves...
Which is just as well - because a couple of hours into the trip, after landing in the Grand Canyon for a picnic breakfast, our pilot told us "I've got some warning lights here on the dash and I don't know what they're telling me..." and we had to go land in an airport (which was more like a motorway service station) in the Arizona desert. After a couple of hours of us boiling & hungover in 40 degree heat while they tried to fix the helicopter, we were told we could get back on board... Only to get maybe 20-30 feet in the air before the pilot told us the warning lights were back and we needed to land again.
They then decided there was no way they were getting that helicopter back in the air, so the company flew a different helicopter out to come and get us and finish the trip.
When I look back now, I'm amazed how calm I stayed and that I got back on - but I don't think I would now. And especially after learning more about what caused this crash, or reading some of the comments in this thread...