Ideal for short-stay visitors, this scenic Golden Circle route through southwestern Iceland features excellent scenery and major sights. Here is a link to a Lonely Planet article about the route.

Gullfoss

During the Golden Circle there are three main stops; Geysir, Gullfoss, and Thingvellir, and some companies also include the new geothermal power plant of Hellisheidarvirkjun and/or other small stops along the way. There are lots of different tour types - By Bus, minibus, and by super jeep. The bus tours are good value, but are pretty basic. The minibuses offer a more personal service. The Super Jeep tours are expensive, but if you are adventurous and can afford it, it's great fun driving with the modified vehicles over the glacier. 

 Geysir

It's generally possible to drive the Golden Circle route during the winter period in a normal car, and well worth the effort - the main sights are quieter and spectacular in the snow and ice. However, it is very important to check road and weather conditions; the official Iceland road condition website gives comprehensive and up-to-date information. It is also a good idea to check the weather forecast, the Icelandic Meterological Office is a good source of information.