We've taken to doing most of our walks overnight or in the very, very early pre-dawn light. Or even camping out on the summit to get sunset and sunrise. We always walk with our dogs and summer days are too hot for them. Morning and evening light makes for better photos too. Not done enough yet to be able to advise you though.
We're always on the lookout for great hills. Our preference is:
a) Not too long or tricky a walk (because our dogs are a handful!)
b) Because we're into photography we generally want some foreground interest as well as great views. So rocky summits are good. Hills that have worked well for us so far are the Cobbler and The Storr on Skye.
Looking down onto the Sanctuary from the great cliffs of the Storr - late May.
The Cobbler in late April - I think the sun might now be rising from behind Ben Imme so perhaps not so good? Winter would be best for here I expect.
Sunrise and sunset is always moving - what works great at one time of year can be pretty dull at another. To find out exactly when and where the sun will rise and set at any given place in the country (even taking account of height above sea level) there's a handy little program called Stellarium (
http://www.stellarium.org/). Just enter your location and it will show you exactly where the sun, moon and stars are at any given moment in time.
Sorry I can't be of more help. But I'm very interest in answers to this too!
Alistair, love your photos!!