After spending a week in Iceland.....I will offer these ten bits of advice on a trip there.
1. If you go.....it'll have to be by Icelandic Air. From Frankfurt (3.5 hours) or from Dulles (5.5 hours). It's a good airline with reasonable prices. If you go for the regular seat.....be prepared for an email about four weeks prior to the trip on a chance to upgrade (to bid on the upgrade to business-class). The least you can offer is 120 Euro each way. The plus side of this is a better seat, more leg-room, food and drink on the flight leg, and a business-lounge visit for that leg. I regard the Keflavik Icelandic Air business lounger to be five-star and worth the extra money.
2. July and August mean that it's summer time. The high temperature will be 20 C maximum. Most days will be near 14 to 16 C. So, don't go and expect hot temperatures, and you need a real jacket with you. I wouldn't advise going in the winter months.
3. Driving in Iceland is simple. The urbanized area around Reyjkavik to be like any town in the US with 150,000 people. Once you get five miles outside of Reyjkavik.....it's strictly rural in nature.....two-lane roads and one-lane bridges. Max speed is 90 kph. Don't go and rent some upscale vehicle. Buy plenty of insurance because of the forty-odd problems that you run into (ash from the volcanoes for example).
4. Food is basically limited to lamb, fish, and expensive beef options. If you do stop for a burger.....don't go expecting anything great.
5. Beverages. Beer, wine and spirits are expensive. You can only buy these at the pubs or at state-run liquor shops. The airport has a beverage shop at the baggage area, and I'd strongly recommend you pick up a six-pack or two.....along with a bottle of booze.....there.
6. Minimum stay? Five or six days really don't cut it for seeing the whole isle. You need two weeks to do the route-one circle of the aisle and to experience the glaciers, Blue Lagoon, and everything else.
7. Nothing is cheap. Don't be shocked paying $100 for a good evening dinner with two drinks each for a couple. There are small diner-like operations where you can go at $40 for some fish-and-chips with a Pepsi.
8. Everyone in Iceland is friendly and speaks to some degree English. They like visitors and love to hear good things about the Island. Crime is almost non-existent. I could not find anyplace that I'd consider as a no-go location while there.
9. Pay attention to maps, and stay off extreme gravel roads in the heart of the country.
10. Whether intentional or by accident.....it's like a large Viking-Disneyland with enticing views and landscape that is unforgettable. It is one of those trips that you return from, and spend hours looking at pictures and feel enchanted by the nature of the island.