PietSkiet, you will definitely enjoy the area. I did a few TR's what to expect at Storms River/Tsitsikamma and Wldernis - GR - Tsitsikamma
and GR - Wildernis
If you stay in Storms River, I assume it is the village, it is a beautiful town and there is a special place where you can enjoy some food and milkshakes from the sixties - Elvis and Marilyn's place - a must visit and enjoy the décor. It is next to Canopy tours which is also great fun to do. The Big Tree is near by just off the N2 and also a nice trail to walk for children enjoying a bush experience. Nature's Valley is nearby, but you will have to go through the Tollgate and just after you have gone through there is a road to the left to NV. Some beautiful scenic views from the top and one can enjoy some lovely walks on the sandy beach with river flowing into the sea.
I will recommend a drive to Wildernis, but on the way there, you might be distracted by a number of different sanctuaries and farm & craft stalls. Enjoy a riverboat ride on the Keurboomsriver and have a picnic on one of the sandbank up the river, do a hike on Robberg - near Plettenberg bay, enjoy a walk at Garden of Eden and even Valley of the Ferns just before Knysna. Then in Wildernis, do the gravel road just after you crossed Swartvlei after Sedgefield and visit some great bird hides. The list is endless and you will have a great time, especially the great farmer's market Saturday mornings at Sedgefield -take enough money, be warned as you will like a lot of things to tast and buy.
As for travelling from Graaff Reinet, I am not sure which road you intend taking, but I love Mountain Zebra NP and just after Craddock, stop to buy some 'dagga' at a well known farmstall with nice filter coffee, roosterbrood and other lekker boere kossies.
I can go on and on to give you a lot more to do, but you will enjoy every minute of it - Enjoy.
You are welcome to pm me for more specific details as we visited most places over the past few years.