Been there on two occasions and thought it was very special. Angkor Wat spread out over large area, particularly if you want to see the smaller sites to the main ones people visit.
Whether you need 3 days? – depends how ‘in’ to it you are.
With a mate, we did our own thing going round on bikes, rather than jumping in a minibus, tuk tuk or organised tour. But it was hot and sticky and I suggest you’d have to be reasonably fit. Shame so much has been damaged/stolen, but still impressive. Interesting to see how the temples had to fight being reclaimed by the forest. Unless they’ve carried out improvements, watch out for the place they all climb to witness the sunset. Madness and dangerous getting down again.
I stayed quite close to Angkor Wat itself at Palm Village.
www.palmvillage.com.kh. Very nicely done, not grand, bit difficult to find, but enjoyed. So very good for temple access, but you’d have to get transport into town. Maybe you’re looking for something more upmarket?
And, if you were travelling over border at Aranyaprathet, I hear the road from there to Siem Reap is greatly improved. Before? – an absolute nightmare, car or bike.