North Wales in May

Yes the bus from Beaumaris to Caernarfon (hourly) is a change in Bangor- total journey time around 90 minutes.

I understand totally why you would want to stay in both towns, that would be my choice too- Caernarfon especially for family history reasons in my case.

But in purely practical terms I wonder if staying in either/or and doing day trips to the other makes more sense.

In fact, again in practical terms, i wonder if 4 nights in Bangor (between the two) may be the answer.

Yes buy tickets on board, yes contactless, yes they will accommodate carry on size bags.

You can change bus in Porthmadog for Harlech (an hourly service- the #G23) so much more frequent than the train. That bus continues on to Barmouth for connections north and south via another change at Dolgellau (as another choice from the train, although the train ride down the coast is a great journey).

While at Harlech you could also consider doing the lovely Tallyllyn Railway from Tywyn (a stop on the Coastal Railway).

The Welsh Highland Railway is not designed post Covid to be a point to point experience and can't be booked as a one way trip on line. You would need to do that by calling them or visiting the booking office at Caernarfon a day or two before. It would depend on availability after round trip part way passengers are taken into account.

It is not at all cheap, but if you can get a booking, is totally worth every penny of the fare.

Each of the castles only take a couple hours to visit so you’d have plenty of time if spending two nights. For me, that’s more than enough time in each town. We had a rental car and based ourselves in Caernarfon to visit the other places. The castles are the main draw in Caernarfon, Conwy, and Beaumaris and there’s little else to those towns. Harlech castle is off by itself and not right in town if I remember correctly.

Picking up on isn31's comments about the Welsh Highland railway, the timetable varies depending on the day. Looking at this years timetable, on the Wednesday of half term this year, you could only get a train from Caernarfon to Beddgelert. It also takes just over two hours. The bus will be a lot quicker.

Just over a day will be ample for each place. In Conwy it is also possible to walk round part of the walls and there is also Plas Mawr, a restored Elizabethan Town house in the centre of the town which is well worth visiting too. It is also worth walking across the old suspension bridge for views back of the castle.

Beaumaris - there is also the Goal.

Caernarfon - also check out Segontium Roman fort .

Harlech Castle is on the edge of Harlech but only a few minutes walk from the centre. Do catch the bus to Harlech and not the train. Village and castle are built high on the cliff. The railway station is at the bottom of the cliff and a very steep walk up to the village. The bus will drop you off on the village.

If time allows, think about a side trip to Criccieth for its castle. It was originally a Welsh castle but refortified after being captured by Edward I, who added an extra storey on the gatehouse towers giving it its characteristic appearance today.

When in Conwy, do take a trip to BODNANT GARDENS. You will need bus 25 from Llandudno Junction *which is about 1 mile east of Conwy - guess you can take a connecting bus? The gardens are at their best in May. This trip will take most of a day. You should also go the short distance (from Conwy) to visit LLANDUDNO and perhaps take the tramway to the top of the Great Orme.
* Select all stops. https://www.nationaltrust.org.uk/visit/wales/bodnant-garden

When in Porthmadog, I think you should also go to visit PORTMEIRION.

If you can do the Welsh Highland Railway one way from Caernarfon to Porthmadog, it is well worth it. https://www.festrail.co.uk

After Harlech, suggest you take the bus down to BARMOUTH and have a walk around before proceeding south of the Cambrian Coast Railway (normal trains). ( isn has already tipped you off about the Talyllyn Railway which goes from Tywyn).

https://www.visitwales.com/destinations/north-wales/eryri-snowdonia-mountains-and-coast/48-hours-barmouth-and-harlech

Personally staying in one place and doing day trips makes much more sense - Conwy, Beaumaris and Caernarfon particularly are close to each other and each town is not particularly big to explore. This would also give you time to do other side trips to places like Llandudno, Bodnant Garden, Betws-y-Coed, Beddgelert and so on.

If you could consider hiring a car (there is both Hertz and Enterprise in Llandudno Junction) this would give you so much more freedom to do this, but equally it is still possible on public transport with a bit of planning.

Harlech is the tricky one out of the four to get to via public transport hence it might be worth staying there, but the other three are easily visitable if you stayed in one place like Conwy.

If you did hire a car I would go for somewhere central like Trefriw or Betws-y-Coed and then none of the four castles would be more than 45-60 mins away. Would mean a much more relaxing holiday and you would see so much more in 7-8 days!!!

Thanks for the replies and suggestions. @isn31c, thank you for the bus confirmations. So far still in the planning stages and researching feasibility of using just public transport.

I prefer a slower paced trip and on past trips I have enjoyed staying in smaller towns and exploring on an evening walk after the day trippers have left. That is what led to my initial thought of staying in each town rather than day tripping.
Harlech may be the biggest challenge of the group, but still looking at options. If I cut Harlech, what recommendations are there for alternate places after Caernarfon that would be sort of on the way back towards London (for flight home)? Is Shrewsbury worth a stop?
Also considering a visit to Llandudno, either as a stopover between Chester and Conwy or as a side trip from Conwy.

Llandudno was a nice town. It has statues/sculptures of Alice in Wonderland characters spread throughout town. Shrewsbury is nice to walk around. Pontcysyllte Aqueduct Was a nice visit as was Iron Bridge. Near Iron Bridge is Blists Hill Victorian Town. If you’re into ceramic tiles, there’s also Jackfield Tile Museum. While I haven’t been to it, Much Wenlock is supposedly a cute town.

As I posted above (and so did Wasleys) I don't believe that Harlech is at all difficult (if you cut the steam railway out and just do it by bus from Caernarfon.)
By the way this week Tywyn (the Tallylyn Railway) has opened a new exhibit- an exchange siding showing how the slate the railway had brought down (the original purpose for the railway) was transferred to the standard gauge wagons for travel to it's onward destination. This is a unique exhibit.
Oh and Caernarfon Harbour was very much built round the slate export trade- welsh slate was exported all over the world.

From Harlech or Barmouth the train will take you to Shrewsbury- change there for Birmingham then London Euston.

Or change there for Newport (Gwent), change there for Reading and then the rail-air bus to Heathrow.

Either way there is no reason why you can't break your journey for a night or two in Shrewsbury or Ludlow or Hereford (the latter two if going onwards via Newport).

You could still do the half route steam train to Beddgelert on one of your days in Caernarfon. TBH there are so many things to do from Caernarfon by public transport you will have to be selective- you (not us).

If you want to stay 2 nights in Conwy, 2 in Caernarfon and 2 in Beaumaris that is totally your choice. Many on this forum are averse to frequent hotel changes, but it is YOUR vacation, no one elses.

Also considering a visit to Llandudno, either as a stopover between Chester and Conwy or as a side trip from Conwy.

Llandudno is only a few miles from Conwy and there is a frequent bus serviced between the two. It is a pleasant Victorian seaside town with pier and traditional punch and Judy Show. There is also the Victorian tramway uo the Great Orme.

I'd do it as a side trip from Conwy - possibly building in an extra night there.

Shrewsbury would work well as a possible stop after North Wales. It is an attractive black and white town on the River Severn with an Abbey. If you are 'into' social history then a day at Blists Hill Victorian Town is well worth considering.

• Llandudno definitely as a side trip from Conwy or vice versa - they're very close to each other
• Shrewsbury is a nice town on the river with some beautiful buildings and is nice for a night with some good cafes and restaurants - nearby Ludlow is a lot more pretty though!
• The castle in Harlech is stunning but there is not much else there and the town is very small, but going there would get you to the trainline to loop back to Shrewsbury etc

An alternative after Beaumaris / Caernarfon would be to get the Sherpa bus from Caernarfon through the mountains to Betws-y-Coed and have a night or two there - you can then get the train back up to Llandudno Junction for the mainline to London. This would give you a spectacular bus journey through the mountains - they are the one thing missing from a perfect trip as all the castles are on the coast :-)

Sherpa bus

You could even stop at Llanberis en-route (between Caernarfon and Betws-y-Coed) and tick off Dolbardan Castle at the end of Llyn Padarn (a lake) - it is in a spectacular location.

Whatever you decide it is looking like a great trip!

Thanks everyone.
@brandybob, thank you for the Sherpa bus recommendation. I really like the idea of hiking in Snowdonia for a couple of days after seeing the castles along the coast, maybe with Betws-y-Coed as a base.
As with most trips, I won't have time to see or do everything I might like to. So I prioritize and hope that I can return sometime to see what I missed.