If it's not too late...
Dartmoor.
Both coasts (N & S).
Exmoor (shared with Somerset).
The rivers Dart and Exe from the moors down to their estuaries.
IMO Torbay is best avoided between Easter and October BUT it does have some gorgeous beaches and Paignton Zoo as well as other attractions.
IMO there are 2 zoos worth a visit (if they're your thing and/or you have kids to keep amused); Paignton and the Dartmoor Wildlife Park at Sparkwell, just off the A38 near Plymouth. Paignton has a larger collection but DWP is better for photos - the big cats are behind a deep ditch and wall so no fences or glass to shoot through (Tigers, Lions, Jaguar, Cheetah) It was the subject of a TV series and the film "We Bought a Zoo" is based on the story.
The lighthouse on Berry Head near Brixham has (IIRC) the distinction of being both the shortest and highest lighthouse in the UK. (It's short because it doesn't need to be tall since it's so high!).
Brixham also has the attraction of Mifsuds on Bolton Road (Google them!), a veritable treasure trove of 2nd hand (and new) photographic kit. BEWARE!!!
Can only agree with all the ideas given above - bring plenty of storage (and maybe a laptop to back-up to - we have that 'lektrikkery down 'ere now!)
Hope you have a great time - come again!