We didn't take the Golden Circle excursion offered by CMV as they charged far too much for the trip. We went into Reyjavik and took a locally-based providers Golden Cicle tour instead - a far broader itinerary that that offered by CMV and at less than half the price charged by CMV. Amongst other things, we saw the Gullfoss waterfall, the geysirs, the Thingvallir Viking parliamnent site, lava fields, and a geo-thermal power plant. My only regret was that going out into the country side, we had no time left to explore Reykjavik - but maybe that's a good excuse to return there someday.