Nice pictures, I have been to all of these spots!
@Newpetlover Cornwall, Devon, and the Pembrokeshire Coast (and Snowdonia, Lake District, Scotland…) are among my all-time favorites in the UK. I’ve walked the entire South West Coast Path, as well as the Pembrokeshire Coastal Path (and pretty much every other National Trail in the UK - haha). I simply love Cornwall. If I were to die unexpectedly while traveling, I hope it would be here, as this is where I’ve left my heart.
Now to your questions. It’s difficult to choose a single place, but fortunately, Cornwall is very small, and you’re never far from the coast. I believe I’ve read that you can reach the coast within 20 minutes from anywhere. Public transport, in my honest opinion, is rather poor there. It depends a lot on whether you go during the season or not. In summer, you might have better luck, but it’s also quite crowded then. I usually go there with my own car. But you need to know that they drive on the left, and the lanes are often single-track. When there’s oncoming traffic, you need to know how to reverse. I’m always surprised that many Brits aren’t very good at this. 
There are accommodations aplenty there, as it’s the top holiday destination for Brits. But remember, it’s an island, and the British are numerous, so you need to book quickly during the season. Wales is much more remote, but of course, everywhere beautiful gets crowded, so it’s the same there.
My favorite place is down in South Cornwall or the Exmoor, Lorna Doone Valley, but it really depends on what you want to do. Don’t miss out on Cream Tea!