We traveled all around Tassie for our honeymoon, it was great!! Did HEAPS of stuff, jet boating, caves, Port Arthur, zoos, seal cruise, West Coast Wilderness Railway, Cadbury factory...you name it, we did it!!
I don't think we'd do anything differently. We were so busy which was kinda tiring. But we still agree it was the best holiday we've ever had.
My fav parts were the boat ride over there as it was so exciting rushing from the wedding to catch the Spirit, the zoo where we got to hold a baby wombat (SO CUTE!!), ghost tour of Port Arthur, all the conversations DH & I had all those hours we spent in the car. Stanley was the first place we stayed at, a little house called The Bakery. We loved it so much we used it as inspiration for our renovations. We also stayed in Launceston, Ross, Port Arthur, Hobart & Strachan.
We didn't have kids when we got married though so can't comment on that. If we did I'd probably have left them with someone I really trusted, as it was so nice having that time with just DH & I after all the wedding stress. Plus we were just non stop the entire 3 weeks & if we had kids with us it would've been much different.
Good luck planning your honeymoon!!