Personally, I'd go Peninsula first,Hibiscus,next choice and Sheraton last.
My decision is purely based, that you'd love Peninsula being a child free resort, on the Esplanade,can get pool or ocean views,breakfast overlooking the ocean,close to all amenities, such as shops and restaurants and patrolled beach at your doorstep with the choice of relaxing on sun lounges and beach umbrellas ( that can be hired)at the beach if you'd like total relaxation for an hour or all day.
I would also look at only doing tours every second day and relax in between and enjoy your free time at the beach,lunching,shopping,having a massage...
Wavelength is a good choice for non divers,with small nimbers a great tour choice.
Next ,Tony's Tropical Tours to the Daintree/Cape Tribulation and Mossman Gorge, a great tour, with great feedback and reviews.All day tour and again another reason to have a rest day after it.
Once you'd done the Reef and the Rainforest( the really must two to do), the 3rd choice would really depend on your interests.
Suggestions, an all day tour to Skyrail/Kuranda/Tjapukai.
Breakfast with the Birds at the Rainforest Habitat,where you can see Australian natives up close.(Koalas,kangaroos etc)
White Water Rafting, if you're adventurous.
Hot air Ballooning,if the budget permits,or half day sailing to Low Isles, leaving noon and returning as the sun sets, quite romantic..just to name a few.
There is so much to do in the area, you centainly won't be bored,if you'd like to do something in particular,let me know for more suggestions.