Hello The Smiths,
I have not yet been on the Port Davey track, but I thought I would add a few words as someone who also comes from outside of Tasmania and who went for some walks there for our honeymoon - 25 years ago.
I know of one couple who did the Western Arthurs for their honeymoon! - but they were well hardened walkers familiar with that part of Tasmania. There was another couple, who were also experienced Tassie walkers, who did Frenchman's Cap - but the bride had to have 2 people to help lift her out of the mud
For me - Tasmania has so many good walks that I tend to be somewhat selective trying to maximise the return on effort.
For our honeymoon we did various day walks all over the island [Mt Zeehan, Mt Owen, Mt Rufus, Schnell's Ridge, the Tarn Shelf at Mt Field and Cape Huay] and an overnight hike around the back of Cradle Mountain. It was fantastic. We also took the boat for a quick return trip to Narcissus Hut up Lake St Clair.
It sounds like you have not been hiking in Tassie yet, so I suggest you focus on what you want from a walk [ie do you want a generally flat walk with mountain and /or coastal scenery, or a more challenging walk with climbs and 'alpine' scenery. Do you want to treck for several days, or do shorter overnight or day walks?] There will be a number of options as others have already suggested that can be relatively easy but also quite brilliant for the variety of scenery.
Apart from some short round trips into the Cradle Mountain - Lake St Clair NP - particularly Pine Valley and around Cradle Mountain, I would also recommend walks into the Walls of Jerusalem, around Mt Field or with a bit more risk, walking up to High Camp Hut and visiting Mt Eliza / Mt Anne.
One day I may get to the Port Davey track, but it is not high on my list.
I may be mistaken, but apart from the remoteness, I suspect there may be no others on the track which will add to the isolation. And there are some tricky sections easily affected by weather (flooding rivers and the sea crossing - both covered in the link from frank_in-oz). The big plus for me would be the chance to climb Mt Rugby, but it seems like a lot of effort for less return than you would get elsewhere.
If you really wanted to go into that area you could consider flying into Meleleauca and walking down to the beaches towards South West Cape before walking back to fly out again? Maybe no further than Ketchem Bay. That would have more appeal to me. Its still very remote, but seems to have more interest and less hazards than the Port Davey track.
Anyway - good luck with your plans. It is such a great place to go trecking in, but do plan to be safe as well.
eggs