If you are visiting Tangalle then Frangipani's is the place to stay. I thought I was only going to stop for one night on my way east but ended up staying almost a week- and only left because I had to get to Colombo to catch a flight! The rooms are spacious and comfortable and the location beautiful. Although there is litter elsewhere on Tangalle's beaches, the beach in front of Frangipani's is always impeccably clean. There is moderate to strong surf (that makes it more fun, right?) but once you get past the breaking waves the water is lovely with no currents to worry about. The food is delicious (try the pumpkin soup!) There is a slackline, hammocks, boogie boards, frisbees, balls, wooden puzzles and more.
The staff is what really makes Frangipani's stand out. The owner is very helpful- book activities through him to ensure cheap prices and trustworthy drivers. Everyone who works at Frangipani's is friendly, resapectful, and fun. I am a solo traveler and Sri Lanka is traveled mostly by couples and families. These guys always made sure I had someone to swim with, games to play, dinner partners, and good conversation. Every night they would sit up late playing karrom with me and the other guests. They even taught me to climb a palm tree for the coconuts!
I would definitely recommend staying at Frangipani's, it is worth every cent.