1 vs 2 bases in North Wales (w/ public transport)

Firstly, are you sure that you can’t fly into Manchester Airport as that is much more handy for reaching north Wales? If landing at Heathrow, you will have to firstly reach London Euston station for your journey to north Wales. Pay on the day rail fares are expensive so it is best to pre-book a specific train advance fare around 11 weeks ahead. That means that you must allow enough time to get from Heathrow to Euston and this can be difficult to judge. Trains > www.nationalrail.co.uk and you should book with www.virgintrains.co.uk but note that they don’t stop at Conwy (Conway) but they do stop at Llandudno Junction = 1 mile to the east. However, I would consider making Chester as your destination for the first night and proceeding to Conwy/Llandudno the next day.https://www.visitengland.com/things-to-do/chester

Spend maybe 2 nights in Conwy (a trip by bus to Bodnant Gardens might be considered).https://www.nationaltrust.org.uk/bodnant-garden

I would then up sticks and go to Caernarfon or Porthmadog for maybe another 2 nights. Caernarfon is more handy for Llanberis & the Snowdon Mountain Railway; Porthmadog is more handy for Portmeirion Italian style village. The Welsh Highland Railway links the 2 and should be used at least one way for a transfer:> https://www.festrail.co.uk

A railway goes south to Aberystwyth but you must change trains at either Dovey Junction - in the middle of a vast marsh - or at Machynlleth. If staying at Aberystwyth, I recommend :>https://www.rheidolrailway.co.uk

No railway directly links Aberystwyth with south Wales. To use the trains, you would have to go the long way around via Shrewsbury in England. However, it can be done by bus/coach and the services of Traws Cymru beginning with a ’T’ - allow you to go for free at weekends - well at least they do at the moment.http://www.trawscymru.info/free-travel-on-weekends-1/
If using local buses to go south of Aberystwyth down the coast, Aberaeron is a pleasant place to break the journey for an hour or so >
https://www.cardigan-bay.com/aberaeron-cardigan-bay.php

For public transport in Wales:>https://www.traveline.cymru

Rail map:>http://www.nationalrail.co.uk/static/images/structure/css/nationalrailnetworkmap.pdf

Thanks James - Will def. take a closer look at Caernarfon and Porthmadog. Seems as though there are pros to both from what I've read on here?

As for my flights - I already booked Heathrow so I'll be sticking with that - BA didn't have direct flights from Boston and I use their points for flights, and the cost with connections was 4x more than what I paid for my round trip airfare out of Logan. So I guess I'm stuck with Euston (which I am a bit nervous about booking correctly with the timing situation).

You may like to consider doing the trip in reverse as it would be easier/cheaper to reach say Cardiff as your first stop in Wales. So, let's assume that you land at Heathrow. You go to Heathrow Rail Station - which serves Terminals 2,3&4 and has free links with the other terminals. Ask for a one way (single) rail ticket to Swindon (HAF > SWI via HAY = Hayes & Harlington). Don't let them get you one via London Paddington as it will cost MUCH more. The ticket will cost £27.20 providing you leave Heathrow on the 9.52am or later. (It must not be the express service to Paddington but a stopper). (8.22 or later will cost £35.40). Then, ask for a Swindon > Cardiff off peak return = £16 for the 11.14 or later from Swindon. (If you want the 11.14 or 10.40 from Swindon to Cardiff, it will be £18.50). So, using the cheapest off-peak trains, we get a total pay on the day price of £43.20 from Heathrow to Cardiff. The first bit from the airport yo Hays & Harlington only takes a few minutes and the trains are every 30 minutes. You will arrive on Platform 4 and must go to Platform 3 for a train going west that stops at Reading. Once at Reading, you simply wait for the next train going to Cardiff. These are hourly on weekends and half hourly on weekdays. You don’t have to get off at Swindon - we have simply ‘split’ the tickets at this point as it reduces the price.

If you want to buy advance tickets, then pay on the day for Heathrow (HAF) > Hayes & Harlington (HAY) = £6.30 and then have a pre-booked Advance ticket - which can be had for £19 from HAY > CDF. For this, you should be on a specific train out of Reading.

www.gwr.com will have more information about the fares & schedules for this route - should you choose it.

Some people heading to Wales from N. America fly into Dublin and then take the ferry to Holyhead or fly from Dublin to Cardiff.

Thanks James - I was really hoping to head into Cardiff first as it seemed much easier, but unfortunately due to a specific commitment I have in Cardiff the first week of August followed by Oxford and London, as well as work commitments back home the week after that, my only option for additional Wales travel outside of the Cardiff area was before my days in Cardiff, instead of after. Fingers crossed Euston to Chester isn't THAT terrible and it all works out :)