One option that we had selected as part of local site seeing was a trip to Kelaniya Rajamaha Viharaya. It is believed that this is one of the 3 places in Sri Lanka that were visited by Buddha. Buddha visited the site to quell a quarrel between two Naga princes who were fighting over a jewelled throne. After Buddha showed them the futility of their quarrel, both of them converted to Buddhism and offered the throne to Buddha. Buddha refused the offer.A pagoda was built at the site. This throne was buried in it as a relic. The pagoda was destroyed by the Portuguese in the 16th century. It was later rebuilt in the 18th century during the Dutch rule. The temple has very good painting depicting important historical scenes. You can also see the statue of sleeping Buddha over here.
It is traditionally believed that Vibhishana, Ravana's brother, moved the capital of the kingdom to Kelaniya after Ravana's defeat. There is a shrine dedicated to Vibhishana here.
We had our lunch at Green Palace Hotel which is very near the Global Towers. I would recommend it for its Indian fare. It is economical. Especially loved the Chole Bhature there.