From Colombo to Nuwara Eliya
Assuming that you have made your journey up from Colombo on Day 1, visiting many of the location listed above on the Kandy - Nuwara Eliya route, you should still have some day light left to explore the town, and maybe finish off with tea at the grand hotel or the grand hotel cafe.
There is little to do in town at night, and the roads do get very misty by around 7PM. As such I would not advise travelling anywhere out side of town too late. Get a early night, as you should probably visit Horton Plains National Park on Day 2
If you do intend to visit Horton Plains it is vital that you get up very early and set off to reach around 7 am, this means leaving Nuwara Eliya town at around 6:15AM. The reason for this is to get a chance to see the precipice at Worlds End, which is a steep drop mentioned in the section about Horton Plains National Park. However you should plan this journey based on the weather conditions for that day.
The trek should take you up to lunch time, and as such you should probably take a packed lunch, or stop off at the farm cafe at Ambewela farms, which is on the way back. More information on it above in the section on this.
The Nanu Oya rail station is also a good place for some great photos, which is also on the way to and from the National Park.
You should also stop off at the Meepiliama Reservoir and Kande Ela forest, both of which make for good photos, and are very scenic spots. More information on both these spots above. If time permits, also visit the strawberry farm which is located a short distance away from the this.
This should take you to the end of day 2.
You should start off the day by visiting Lake Gregory, and Single Tree Hill, both of which offer fantastic views, more information in the section above. If time permits you should go for a drive around the lake, or perhaps go peddle boating.
Your next stop should be Victoria Park, which should take you to around lunch time (1-2pm). Why not try one of the food out lets in town, there are a few located in the main street. Refer to the section on where to eat for more information on this.
After lunch you should visit Hakgala Gardens, for more information see the section above. There are a few good photo spots on the way, including a hindu temple and lush tea estates. This should take you to the end of the day.
Start the trip back to Colombo early in the morning, use the A7 route, rather than the A5 refer to section above on routes. This will allow you to see and photograph many of the spots mentioned in the list in the section above. Do stop off at the tea pot for a mid morning tea.