I wish I could award best question!
I am from Devon and think it is one of the most outstandingly beautiful places in the world.
Some places to consider in Devon are the South Hams - Salcombe in particular - and have some Salcombe Dairy Ice cream while you are at it.
A great hotel to visit is on Burgh Island - the setting for a couple of Agatha Christie novels. The island is connected to the land at low tide and at high tide a sea tractor will drive you through the shallow water out to the island - great fun. The hotel is art deco style and very beautiful.
Topsham is a very attractive small town on the river Exe - and has a high concentration of great pubs.
In Cornwall you will definitely need to visit Padstow and Rock - while you are there hire a bike and cycle along the camel trail. There are world class restaurants in Padstow - check out Rick Stein's place.
Another fun thing to do is head to Lyme Regis on the south coast of Dorset and look for fossils on the beach. Just take a big hammer and start cracking rocks on the beach - you are almost sure to find some.
Thought I'd died and gone to Devon
Enjoy!