Oh, you'll have a lovely time.
I am there very often.
Make sure you get an ice cream from the ice cream parlour in the centre of the village. People come from miles around. In the evening, you can get pizzas there too and bring your own wine. The pub opposite, the Tanronnen is lovely.
Drop into the visitor centre to get some maps for walks-don't just do the central village river walk. There is so much more to see than that. Then, when you see the Gelert's grave, carry on down the path a bit to the little cottage-there's a nice surprise in there.
The train from Caernarfon passes through the campsite. It's well worth a trip.
Down the road Porthmadog is a nice town. My kids love the crazy golf in the park. A visit to Portmeirion is essential too.
Just outside of Beddgelert is an RSPB post where you can check on progress (every year) of only pair of nesting ospreys in Wales. Watch CCTV,look through binoculars and so on.
Drive further on to the little village of Croesor at the foot of Cnicht which is magic. The little school closed a few years ago-only 4 kids.
It has a great little art gallery and cafe and most magic of all, an open air swimming pool that one of the villagers built! It can be filled by diverting the stream. If you find the guy who did it (Tudr) he will probably do it for you. he did for me a few weeks ago! Takes about 45 mins. to fill completely.
For rainy days, Caernarfon has a great softplay centre in an old church (The Hwylfan/Fun Centre). Near it is a (very SN friendly) arts centre/cafe called Galeri which has films,shows, cafe and so on. It;s on the dock so nice to walk by the sea and see the huge fish in the marina. By the castle there's the 'Floating retaurant' which does great fish & chips. You can by crabbping lines in a little shop nearby and if you go over the bridge, you have the beach and a good park. You can drive all along this (someone will have to point you to the road to do it-not obvious),it's called the Foryd and is so wide and open and peaceful. We cockle and have picnics there a lot.
I would really really recommend a visit to a great cafe called 'Caban' in Brynrefail near Llanberis. Lovely place, fab food and wonderful safe garden to play in and afterwards you canstroll down to the bridge and very shallow lake to paddle.
If you are into archeology, Caernarfon has asmallbut interesting museum on remains of its Roman garrisson.
Re your points, I agree.The key is flexibility to meet the needs of the people served. The NHS isn't flexible at all in this way, which drives me nuts.