We had a very, very positive experience with our Guide to Iceland self-drive tour. Overall, Guide to Iceland delivered exactly what was promised and made everything very easy. I think they really exceeded themselves in the quality of the hotel bookings.
A few notes: We traveled in March and opted to go for a vehicle upgrade to ensure we had 4WD. This was DEFINITELY worth it. I cannot imagine driving some of these roads in a little front-wheel drive hatchback. We got a Kia 4WD and were VERY happy with it!
The accommodations in Reykjavik (3 nights for us because we added a night) were super-nice. The hotel was clean, modern, and very classy. Felt like we were staying in one of the nicest hotels in Reykjavik. (Icelandair Hotel Marina) The accommodations near Skaftafell National Park were out in the middle of nowhere but also felt very posh. It looked like Antarctic research station on the outside, posh hypermodern hotel on the inside. (Fosshotel Nupar)
The hotel in Hvollsvollur was the least interesting. There was nothing bad about it, it was just unremarkable. But that was fine - the place was clean and perfectly serviceable if unremarkable.
Breakfast was included everywhere we went (we payed for the comfort upgrade on the rooms) and we had a private bath in all hotels. Everyone was super-friendly and extremely helpful everywhere we went.
Only minor issue is that we customized our trip by adding a night, and this seemed to cause a little bit of confusion with our booking agent since it took her a couple of tries to get the itinerary corrected. However, it was all sorted out well in advance of the trip and overall the booking agents were very responsive, professional, and helpful.
HIGHLY RECOMMENDED! You will love it.