US to Wales - best way to get there?

"just south of Snowdonia" is north Wales so the nearest international airport is Manchester. Whether that's convenient only you know as you don't give your start point in the US.

There may be more options to fly into Heathrow, though Manchester would be closer. I would forget Cardiff.
Whatever you decide it's not recommended to get off an overnight flight, tired and jet-lagged, then jump into a car in an unfamiliar country.

All travel is a compromise between price and length of journey.

It is a long way all across Wales from London.

Don't do that after a long flight.

Especially if you have never driven a right hand drive car.

It is a long way all across Wales from Manchester, too, just not quite so far.

Don't do that after a long flight. Especially west to east as you won't know how exhausted you may be jet lag. It can be as impaired as driving drunk.

It's a fair pull by train, too. Perhaps break your journey in Chester?

You don't say specifically where you are staying but I think, if it was me, I would fly into Manchester and take the train to wherever you're staying (or close to it) and rent a car there to drive around Wales. If you will be staying in more than one place in Wales then it would depend on your stops and which direction you will be traveling when determining where to fly in to. Could be Manchester, Cardiff, Bristol, London, whichever gets you to your first stop with the least amount of travel after landing and whichever has the best (cheapest, least flight time, etc) flights. When figuring out the best cost be sure to add travel costs after the flight into the final cost.

Depending on where you are headed a coach might be worth a look as well. http://www.nationalexpress.com/home.aspx

I agree with the other posters that jumping off an overnight flight right into a car is a bad idea.

DJ

In 2014 my husband and I flew into Manchester and then got the train to Conwy. Our rationale for this was that we would be fuzzy from the long travel from the western US and that it would not be a good idea to rent a car and drive right off the plane. In addition, we decided to explore Conwy on foot before renting our car from Enterprise in Llandudno. That gave us one full day and two nights to get our wits about us. Enterprise came to our B and B to take us to their office where we did the paperwork. Conwy proved to be a good gateway to explore North Wales.

Some things to consider.
The train station at Manchester involves a bit of walking from the International arrivals area but is well marked and within the airport complex.
It is not a short train ride and it involved a change. (My husband took a nap....I watched the countryside)
Conwy is a request stop so you have to notify the conductor when you get on. (We found the whole experience to be friendly...like they were looking out for the two old Americans)
The streets in Conwy are narrow, and in some cases the traffic patterns are convoluted. However, it is not like driving in a major city and we found it quite easy.
If you take the trains be sure to get early reservations. You can save a lot of money by buying in advance.
Rent the SMALLEST car you can fit in.

We had a Chevy Spark for this trip and found it had room for our two roll aboards and our hand carry in the covered hatch area. We could then leave nothing on the back seat while we were touring. This year we had a Fiat...both were manual transmission and could have used a bit more power in the really hilly areas. The advantage of the smaller cars was that some of the the roads, especially in Wales, are really really narrow.
We had OS maps. A bit cumbersome but had really good detail. I did the navigation, my husband drove. (This year we purchased the card with UK maps for our Garmin for about $70. We did not have the OS maps. We missed the maps, but the Garmin did allow us to plan ahead for the roundabouts and turns. )
After our excursions in the north we drove down the coast to the Cardigan area....then south visiting castles to the town of Carmarthen where we turned in our car and took the train to London. (Enterprise drove us to our hotel in Carmarthen from their office)
Hope this helps.

We are retired in our late 60s early 70s .... just to let you know it is possible at that age. We are active in our lifestyle.

Overall it was a great experience and we have been talking about doing it again.

You can find the train times & fares here:> www.nationalrail.co.uk
Manchester Airport to Conwy is MIA > CNW

You might wish to make Chester your choice for a first night stay:> http://www.visitchester.com

If travelling by train from London (Euston) to Chester/ north Wales, you can pre-book with www.virgintrains.co.uk
(Please note that Virgin Trains do not stop at Conwy but they do usually stop at Llandudno Junction = 1 mile to the east).

www.arrivatrainswales.co.uk - have direct services from Birmingham International (Airport) to mid Wales (Aberystwyth) & northwards to Aberdovey, Barmouth, Porthmadog (south Snowdonia) and Pwillheli.

www.visitwales.co.uk

Regarding cheap flights, there is blog called Thrifty Nomads that has a helpful article titled "How to Book the Cheapest Flight Possible to Anywhere." Step 3 in the article explains how to find the cheapest days to fly if you have a flexible schedule.

I have no connections whatsoever to this blog. I just found the article helpful.

You have received lots of excellent advice here. To continue on what Ann wrote, I would take the train to Conwy. Book a hotel or B&B for a couple of nights. Recover from jet lag. Conwy is a beautiful little village. You will want to see Conwy Castle which is medieval. Also walk around Conwy and enjoy the waterfront and views.

As a day trip from Conwy, you may want to travel about 10 to 12 miles to see Caernarvon Castle, another medieval castle. It is reached from Conwy by taking the number 5 bus. Wales has lots of bus routes. The Tourist Information Centre in Conwy is very helpful with information along those lines. We picked up a lot of brochures for attractions and maps from the TI Centre. They can also help you find a hotel or B&B if you arrive without reservations.

As an alternative to renting a car, there are numerous tour services, with a variety of routes. Some let you design your own tour. This company: www.viptravelservices.co.uk is very good.

If you stick with your plan to rent a car, I think it is a good idea to stay in Conwy and take a day trip to Caernarvon first. After 2 days into your trip, you will have recovered from jet lag enough to get your bearings, pick up your car, and have a safe drive on the roads. Think of the first two days staying in Conwy as a rest period, and a chance to recharge yourselves before your drive.

You wrote, "I don't mind carting luggage around on public transport to get from an airport to a train station, or walking several blocks with my luggage, but my mother is 75 and would have more difficulty." Remember what Rick Steves says about packing light. Take everything you need, but remember not to overburden yourselves.

Have a great trip!

Fly into Manchester. It will avoid a stressful drive from London. It took me 6 hours last week to drive what should have been a 4 hour trip due to car accidents on this route. This is not what you need when you step off the plane! Don't drive straight off the plane.

Spend your first night in Chester. It is worth a look at the Minster and the old city centre anyway. Chester will give you far more car rental places to choose from than any of the small towns in north Wales.