I live here, so this is the list I actually use rather than the one you find on every travel blog. Kandy is small, which means you can do two or three of these in a single morning if you start early enough.
Everything below is free to walk into except the Botanical Gardens, which charge per person at the gate.
1. Kandy Lake, just after sunrise
The white parapet wall running round the water, the old pavilion, and the hills coming out of the mist behind it. At six in the morning you will share it with a handful of walkers. By nine it is traffic and tour buses.
The light comes from across the water early, which is flattering and even. Later in the day the sun is overhead and the lake goes flat and metallic.
2. The rain tree avenue, Royal Botanical Gardens
The avenue of rain trees at Peradeniya is the one place in Kandy that works in the middle of the day. The canopy is so dense it turns harsh noon sun into soft green shade, which is exactly what you want when everywhere else is unusable.
The giant Java fig nearby is worth the walk. Give yourselves an hour inside the gardens, not twenty minutes.
3. The old town streets, late afternoon
Colonial shopfronts, painted and repainted walls, and that narrow light that comes down between buildings in the last hour. This is where the photographs stop looking like a holiday and start looking like a place somebody lives.
It is busy. That is fine — people walking past at the edge of a frame make a picture feel real.
4. The hill viewpoints at sunset
Bahirawakanda and the roads above it give you the whole city with the lake in the middle. Best on a day when the afternoon haze has lifted; on a heavy day you will see very little.
5. Wherever you already go
The most-used photograph from any session is rarely from the famous spot. It is from the tea place you always sit at, or the road you walk down. If you have somewhere like that, tell me and we will build the morning around it.
A practical note on timing
If you remember one thing: the hour after sunrise beats everything else, and it is not close. Second best is the hour before sunset. Everything between is a compromise you make for a reason, not a default.
If you are planning something, message me and I will give you the version of this advice that applies to your dates and your trip.