congrats on the impending nuptials and have a grand time honeymooning!
we have been to cairns a few times now and port douglas a couple of times...know palm cove and have visited trinity

personally id stay in port douglas...theres a lot more to do...more fun at night..more vibrant
than say trinity or palm cove..( trinity is pretty quiet day and night)

cairns...im not crazy about...its good for a visit and if you had kids then the public pool area is fabulous but theres something about seedy about the central area...and the street smells from around the pub corners can be a little confronting

if you have the car it is easy enough to get around...a nice drive up to port douglas from cairns so it is no hassle getting down to cairns in order to access kuranda or whatever else you want to do

we stayed in the centre of port douglas in great ( mantra chain) apartments...did a lot of research and found that much of the accommodation up closer to the harbour end of the main street gets a lot of noise from the pubs so we were very happy to stroll from down our end
mind you, theres lots of accommodation up towards the entrance to port douglas and id not stay there either...im not one to wait for shuttle buses and it is too far to walk into the centre especially in the heat
i always email to ask how old the accommodation is...it seems to get very tired quite quickly ...the sheraton mirage used to be beautiful but when we popped in there for a quick visit i was really disappointed to see how shabby it had become...im not sure if they are now refurbishing it but it sorely needed maintenance when we visited four years ago

One night en route Airlie Beach - Cairns does not give you much time for exploring anything so why drive?

If you do want to drive take at least three days for it. There are 8 hours of just driving ahead of you. If you take up this suggestion get back here and let us know more about the things which interest you and I will give you some ideas of side trips and sights to see.

we are stuck for time and dont want to have another flight so driving seems the best option, leave airlie beach early in morn and stay in townsville just to break up the drive to cairns. 3 days in cairns and 2 days in port douglas is loads to do the gbr,daintree and explore.
thanks for all feedback