One day tour from Reykjavik

Have a three day stop over in Reykjavik. Would like to tour the surrounding countryside. Looking for suggestions, and accommodations, next July.

The classic one-day tour is the Golden Circle of Thingvellir, Geysir, Gullfoss, optionally Hveragerdi. Nearly everyone does it because what you see really is special. You can pay someone to take you on a coach tour, or hire a car and do it yourself at your own pace, trying get out of synch with the coach tours so that you have a bit more space. But there are other choices, and you will have difficulty remaining unaware of the standard tour offer as it is prominently advertised in just about every hotel and guesthouse. But there are also specialist tours, for example specialist tour operators can also take you special places that you need special vehicles to get to, it's easy to google down the tour offer - those may require some pre-booking. Your choice ultimately.

I would recommend you to hire a car, head of to the south coast and take a ferry to the Westman Islands, check out the new lava there and go on a zodiac ride with www.ribsafari.is, you can stay at the islands for a day or head back the same dame and check out seljavallalaug (https://plus.google.com/114132389187171143793/about?gl=is&hl=en) and Seljalandsfoss. I would find than a b&b or farmhouse to stay at over a night , and take the golden circle (or part of it) on your way back to Reykjavik.