@dadpad,
A lot depends on what your own individual tastes are. I really love the British Isles- England, Scotland, Wales and Ireland- but I have English and celtic ancestry, so they're of particular interest to me.
Outside of England, I love Spain because I love latin music and culture and Spanish food.
The southern and western part of France are spectacular in terms of scenery. I've been to Paris- but I prefer more wild and natural settings myself. The French alps, and the Dordogne are beautiful regions and in the Dordogne, you can paddle the river and see medieval and walled villages from your canoe. Of course, if you're a city person - Paris is a must -see- even if you're not a city person - it's spectacular.
Next time I go to France and Spain, I plan to explore the Pyrenees, walking, I've heard they're very beautiful. If you like to hike, there's a pilgrimage through the Pyrennes along the way of St. James. The hostels there cost 3 euros a night.
But if you just want to get to know a specific area- there's more than enough to do and see around England in two or three weeks time. I've lived here four years and I still haven't seen all that I'd like to see and every time I go anywhere , I always feel that I'm coming back to the most beautiful European country when I return to England.