Have you looked at the Hobie Adventure Tandem Island boat (this is the larger version of the AI). If you search youtube for Tandem Island you will see many videos of Tandem Islands loaded down with families. The boat is promoted as a family fun boat, and indeed it is.
Here is one of my favorite TI videos showing 3 large guys on a TI with the trampoline option (which is a must have option, HAKA's are also very desirable for carrying extra passengers (HAKA's are kind of like the wing seats on the getaway).
If you look at the specs on the Tandem Island vs the Getaway you will find the Tandem Island to be much larger than the Getaway (I believe the Tandem Island is Hobies largest boat)
ti vs getaway
length 18.5' -- 16.7'
width 10' -- 7'8"
weight 190lb -- 390lb
sail area 90 sq ft -- 180 sq ft
capacity 600 lbs -- 1000 lbs
One huge advantage the TI has over any other boat out there is the dual Mirage pedal drives, just by pedaling lightly you can propel the boat even in no wind at all at a reasonably fast clip (4-5 mph), both my wife and I can pedal all day long (10 hrs), and get up and do it again the next day. So you don't necessarily need all that extra sail area, keeping in mind that along with extra sail area comes more responsibility and complexity. The Tandem Island is near impossible to capsize, and has proven itself out in just about any conditions within reason (ie.. CG small craft advisory is our limit), which is likely the same limits to safe sailing on the Getaway as well (especially with your family).
If you do get a TI I highly recommend getting the trampoline option, each trampoline has a 200 lb capacity, and is perfect for additional passengers. The boat has 2 seats so the plaque on the hull says 2 passengers on the kayak hull, and 600 lbs capacity. Since the kayak part of the boat can be used stand alone as a kayak (actually a really good kayak).
There is no other boat on the market today that is as versatile as the Tandem Island especially when it comes to family fun. We always carry 6 pfd's on board, and often go out snorkeling off Higgs beach or Tank Island (Key West) with as many as 6 people on board (in safe water and conditions of course). If I had to guess, the boat in the above video is loaded with over 700 lbs of people.
We added a motor (2 hp gas) and extra sails (260 sq ft) to our TI but we use our TI mostly out in open ocean (salt water) for Scuba diving and island hopping in and around Key West, and the Florida gulf coast, but that's just us, everyone has their favorite things to do.
This is our TI on a recent trip to the keys, we kept it moored offshore for the whole week, and went out sailing and snorkeling every day with as many as 6 people on board at times (adults and children), of course when loaded down we stayed in shallow and safe water.
Hope this helps you.