Mr. Gray, you forgot to mention that we also used the time on our last morning to visit the....er....museum.... What a surreal experience that was!
Sarah - I agree with Bob, it's probably a 15-20 minute gentle stroll from the hotel into town but taxis are pretty cheap, especially if you get a group of you together like we did. Everything is concentrated in a very small area and the streets have an easy to navigate grid layout. But, there is a small convenience store quite close to the hotel if you don't want to venture far.
You will be very wise taking lots of layers as the weather changes by the minute. It's always very very windy. I'd also suggest a pair of YakTrax or similar for the Golden Circle because it can be slippy under foot (not great when you are right on the edge of a massive waterfall!!)
Book it - I promise you won't regret it. We had an awesome time....even at the.... 'museum'!
All the best
Mandy