Lamma is pretty cool to hang out actually. it is kinda like a small town and yea, it is isolated and the ferry is not 24hours. Sometimes, u even need to wait for 1 hour for the next ferry.....i had this experience...The ppl there is nice and u cant find those big chain stores there - not even a chain big supermarket.
Even there are just 4-5 train stations from Lantau to Central, but actually it will take u about 45mins.
Tsing Yi is v good esp u work in Central. The environment is good and new. short distance to Central, very convenient.
TKO is also good too.
check this out, this is about renting apt in hk:-
http://www.gohome.com.hk/english/home.asp?