I have read most of the Guanaja forum content and just returned from a 10 day trip to Guanaja Island. We were with a family of 5, including three teenagers, who all thought that this was one the best holidays they had ever had. We are all certified divers, so that was our main activity.
I wrote a review on our accommodations under the heading Villa at Dunbar Rock. This is a spectacular place built on the South side of the island. It is managed by Denis and his family and is absolutely a gem. It is NOT for party seekers, as one is relatively isolated on this rock. More information can be found on the website: http://www.villaondunbarrock.com The food is simple but very tasty and the diving with Denis is second to none. He arranges three or 4 dives a day with picknick lunches and swim sessions in between.
I also spent two days fly fishing and did this with an outfit called Flyfish Guanaja and you can find the website at http://www.flyfishguanaja.com I caught lots of bone fish and saw more bone fish per time unit than in places like Cozumel, Andros, or Belize Turneff. There is not very much tarpon, but there is apparently lots of permit and snook. I did not have any luck seeing and catching them. Their guides are great and the fishing is out of mexican style panga boats. The owner, Steve, is great in responding to e-mail and if he is not there, he keeps in close contact with his guides. All arrangements for pick-up etc were done by e-mail and it worked exactly as agreed upon.
As far as travel, we flew through Atlanta to San Pedro Sula and then had to take a small hopper with Sosa Airlines via La Ceiba to Guanaja. I think that the next time I will fly though Roatan and then with a small hopper from Roatan to Guanaja. I think there are more options this way than via San Pedro Sula.
My ratings would be:
Villa on Dunbar Rock: +++++ (but again: NOT for party seekers)
Diving with Denis: +++++
Fishing with Flyfish Guanaja: ++++++
Travel to Guanaja: ++
Value for money: ++++