G'day Strider
This is a big question!
I have owned several types of kayaks, from calm water to expedition. I currently own a Dagger Exodus, which is an ocean/expedition kayak. Whilst this one may not be appropriate for your parent's needs, I can however vouch for the great design and comfort found in Dagger kayaks. Great chines, even better and more stable when loaded up with gear. They handle chop very well, although I do believe that chop is all about skills as well as the kayak. They are a little expensive however. Great nonetheless.
Prijon, RTM and Wilderness Systems make excellent boats too. There are plenty more, but I guess it's all about retail accessibility, and price. Capacity Sports used to sell Prijon, and so did Canoes Plus...two well known kayak shops here in Melbs. Whilst I'm not a fan of Anaconda, they do often jag some pretty good deals on kayaks. Whilst they may not be big ticket brands, they do have similar characteristics in design to the bigger brands, and much cheaper.
It's important they sit in them (dry or wet...although in-water is far more preferable), and try them out if possible...the size of the cockpit plays a significant role in good paddling technique, balance and comfort (especially if you intend on sitting in it for hours). I've spent plenty of days down at Wilson's Prom here in Vic, where we wouldn't get out of our kayak for 6 plus hours, so comfort is very important, plus...a proper fit makes for a safer experience, as it can be manoeuvred and controlled properly with body position and core stability...not just paddle strokes. I also know that some Anaconda stores have test pools for this purpose.
Other considerations are whether they want plastic or fibreglass (plastic may be more suitable for them perhaps), day hatches, storage capabilities and deck configurations (for when YOU get the kayak bug and decide to throw a sail on it...hahaha)
Tassie certainly has some renown kayak clubs such as the Maatsuyker Kayak Club (
http://www.vision.net.au/~jennings/) or the Tassie Sea Canoeing Club (
http://www.tscc.org.au), so perhaps they could help to direct your enquiries also.
Hope this helps...it's a start anyways.
Jase