Coast of North Wales

In Stow on Wold, the back door of St. Edwards church is flanked by a couple cypress type trees and makes for a nice photo. Conwy is a mere 30 minutes drive from Caernarfon and 11 minutes drive from Llandudno.

I’ll suggest Anglesey. It’s easy to spend a day there. There are numerous Neolithic sites such as, Bryn Celli Ddu Burial Chamber, Penrhos Feiw standing stones, Lligwy burial chamber, and Bodowyr Burial Chamber as well as South Stack lighthouse, and the Melin Llynon windmill. There’s also Beaumaris castle and the town with the long name; Llanfairpwllgwyngyll…gogogoch. There are also numerous walking trails.

If you did decide to take the A5, the Pontcysyllte Aqueduct is worth stopping at. Also near Llangollen is the Plas Newydd Historic House & Gardens and Valle Crucis Abbey / Abaty Glyn Y Groes. Llandudno is nice to walk around with a couple pay parking lots in the center of town. If you’re an Alice in Wonderland fan, look for its characters’ sculptures throughout town. In town it’s just beach, but there are some good views from the cable car. Just up the road from Llandudno is the 6-seat St. Trillo chapel and Holy Well on Marine Dr. in Rhos-on-Sea. In the general Caernarfon area is the Ceunant Mawr Waterfall and Dolbadarn Castle.

Conwy and Llandudno are only 4 miles apart, so not much time for any scenery. In Llandudno, Great Orme is worth a visit for the views and scenery - take the tram up if you don’t want to walk.

Snowdonia is also worth a visit for stunning mountainous scenery.

If you want coastline, then visit Anglesey - the east coast is gently undulating, whereas the west coast around South Stack comprises cliffs. The coastal path around the island is interesting whichever part you walk. If you find yourselves in Moelfre, the sea buckthorn ice cream in the ice cream parlour is amazing.

The Llyn Peninsula has some interesting scenery to the north, but has numerous larger resorts along the south coast. I much prefer Anglesey.

I would visit either Conwy or Caernarfon Castles. Bodnant Gardens just up the river estuary from Conwy is wonderful.

Can I make an alternative suggestion to Caernarfon Castle. It is very similar to Conwy , just bigger but without the remains of buildings inside. The town is also a walled town like Conwy, so you could consider it as much of the same... Instead, why not go to Beaumaris Castle on Anglesey. This is a moated castle and very different to Conwy. It is also one of the best concentric castles built by Edward I and would have been cutting edge technology at the time. It was a real killing zone.

Then do the drive down to Penmon Priory and continue along the the toll road down to the lighthouse at Penmon Point, with its views across to Puffin Island.

There's m ore to Llandudno than the beach... The Great Orme is well going up and has fantastic views. The Victorian Tramway is great fun but does get very long queues in the morning and there can be a long wait. There is plenty of walking on the top and there are the Bronze Age Copper mines which make a fascinating visit too, especially as you are able to walk through some of the original tunnels.

When you go from Conwy to Caernarfon, you can either go via the A55 expressway (coastal route) or the mountainous inland route. The nearest part of the coast which is stunning would be to cross over to Anglesey and head for Newborough (which I see on Google Maps has now be changed to Niwbrch as the Welsh speakers in this area don’t like the English names). You the then head south down to the car park near Ynys Llanddwyn . (Ynys is Welsh for island & Traeth is Welsh for beach).

Bodnant Gardens - south of Llandudno Junction - is well worth a visit - especially in May.

We spent a bit of time on South Stack either side of travelling to and from Ireland via the ferry and fell in love with the area. I did see a great doco on it recently, I will see if I can find the title.
Great coastal scenery, lots of sea birds, a fabulous lighthouse (we climbed up to the reflective mirrors up top). Nice trails up to Holy Mountain. Also Ty Mawr ancient hut circles.
Not sure if it fits your plans but well worth a visit. It's about 45 mins from Caernarfon, just out of Holyhead.
I haven't been to Conwy but absolutely loved Caernarfon. We spent hours at the castle.

The documentary is called Scenic Coastal Walks featuring Kate Humble.

Thank you for all the great suggestions! I think we may decide to visit Ynys Llanddwyn after Caernarfon, then spend the late afternoon and evening in Llandudno. (unless we spend all day exploring Ynys Llanddwyn)

In the event of bad weather - an alternative could be >https://www.nationaltrust.org.uk/plas-newydd-house-and-garden - which is on Anglesey - almost facing Caernarfon.

Another bad weather possibility is >https://www.nationaltrust.org.uk/penrhyn-castle - which is just north of Bangor.

I found Plas Newydd a bit boring (apart from the Whistler painting). Now Penrhyn is in a different category completely - opulence and bling at its best!