We had a go-around a few years ago at Bangkok (the old airport) on Thai Airlines. Daylight, good weather and a very last-minute go-around. We spent a while circling the airport with no information from the crew. During that time all kinds of things went through my mind, all of which assumed some problem with the aircraft (e.g. landing gear broken etc). People were calm but there was a definite tension in the cabin. When the FC did make an announcement it turned out that even though he had been cleared to land the pilot saw that there was another aircraft on the runway so he had to go around. I still thank God that there was good visibility on that day.
I'd much rather that the crew are doing whatever they need to do and that a PA might not be top of their priorities but don't say that passengers aren't concerned in these situations because they are. They don't have to be screaming and praying out loud to be concerned.