Bob,
Gigrin Farm is quite a drive from Rhyl, there is a Kite feeding station nearer at Nant-y-arian but even that would be on the range of your two hours, if not more.
Much nearer would be RSPB Conwy which has flat paths and (I think) disabled ramps, where you would see wildfowl and waders, nearby, Llanfairfechan promenade should be good in November with Red-throated and Great Norther Diver, Slavonian Grebe as well as 100's if not 1000's of Common Scoter with the chance of a Velvet or two (also Paenmaenmawr and Llandulas). With luck you might find the returning American race Black Scoter. There's a good cafe too!
Aber Falls might net you Chough but I suspect would not be suitable for your in-laws, the nearby Spinneys reserve near Bangor is good for Greenshank, Kingfisher and waders and wildfowl.
If Kite is your main quarry then you will probably need to motor south, but as the kites tend to wander in winter you could get lucky in the Conwy Valley. Try Llanbedr-y-Cenin in the Conwy Valley for Hawfinch (the churchyard and surrounding area are as good as anywhere) and you might also get lucky with Goshawk and hen Harrier.
With the A55 now a major trunk road you will be in easy reach of Anglesey, so RSPB South Stack should yield Chough, Raven and peregrine (as well as the out of range Hooded Crows, whilst there are many other good sites around the island such as Penrhyn Bay, Maltraeth, Holyhead Bay & Harbour.
I'm sure there are other BFers who know the area better who would be able to give you some more pointers, and I think there is another thread with site details on so try a search?
Enjoy your week!