Out of these, Castle Hill is the hardest and also the prettiest. It has a lovely road leading to the foot of the hill, then you climb through the trees, round the hairpin, then near the top on the left you can catch a glimpse of the whole valley you left behind. The only problem with it is that it leads you onto the A249, so just get to the top and turn round again.
Only just seen this.
If you want to go mad and make a day of it, to the east of Exedown are a few more. Don't know how to make posh links, sorry.
Birling Hill (heading NNE)
http://www.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=birling+hill&aq=&sll=51.324497,0.421085&sspn=0.038135,0.077162&ie=UTF8&hq=&hnear=Birling+Hill,+Snodland+ME19+5,+United+Kingdom&z=16
Lidsing Hill (heading NNE, approach through Boxley)
http://www.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=lidsing+hill&aq=&sll=51.306955,0.545111&sspn=0.03815,0.077162&ie=UTF8&hq=&hnear=Lidsing+Rd&ll=51.320957,0.556784&spn=0.038138,0.077162&z=14
Castle Hill (heading NNE, comes complete with hairpin)
http://www.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=castle+hill,+kent&aq=&sll=51.292841,0.592232&sspn=0.038376,0.077162&ie=UTF8&hq=&hnear=Castle+Hill,+Kent,+United+Kingdom&ll=51.295552,0.592232&spn=0.01908,0.038581&t=p&z=15
Cold Blow Lane (heading NNE)
http://www.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=cold+blow+lane&aq=&sll=51.292278,0.607896&sspn=0.019188,0.038581&ie=UTF8&hq=&hnear=Cold+Blow+Ln&ll=51.292948,0.610514&spn=0.019081,0.038581&t=p&z=15
Broad Street Hill (heading NNE)
http://www.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=broad+street+hill&aq=&sll=51.283447,0.631371&sspn=0.019192,0.038581&ie=UTF8&hq=&hnear=Broad+Street+Hill&ll=51.285997,0.631714&spn=0.019084,0.038581&t=p&z=15
Hollingbourne Hill (again, NNE)
http://www.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=hollingbourne+hill&aq=&sll=51.269809,0.642357&sspn=0.01909,0.038581&ie=UTF8&hq=&hnear=Hollingbourne+Hill,+Hollingbourne,+Maidstone+ME17,+United+Kingdom&ll=51.271125,0.649867&spn=0.019197,0.038581&t=p&z=15
Out of these, Castle Hill is the hardest and also the prettiest. It has a lovely road leading to the foot of the hill, then you climb through the trees, round the hairpin, then near the top on the left you can catch a glimpse of the whole valley you left behind. The only problem with it is that it leads you onto the A249, so just get to the top and turn round again.