This is one of the best hill stations that I have visited. Its easily accessible, busses ply to the hill top too. just select a decent resort type place to stay. City hotel may spoil the feel. the climate is perfect for a summer get away. I like it best when in early monsoon season( July to August) . The climate is very cold then.
The usual spots are good to see. When you visit during peak season, ensure you start late so that the traffic subsides. Or just go to near by villages and then come over to the main places.
If you happen to visit during off season, Dolphin’s nose trek is a must. its just wonderful. Tiger caves if open is fantastic too. Mannavanur lake is a must visit in all seasons, its a one hour drive from Kodai. Havent visited Berijam but heard its fantastic too!