There are two terminals - the main KL airport terminal and the LCC (Low cost carrier terminal) They are both in same general area but not actually near each other. They are about 70km from the CBD of KL.
When we went to KL, we travelled on Air Asia so arrived at LCC. There were buses that went into town - tickets were very cheap.
From the bus depot, it's easiest to just get a taxi to your hotel.

It's easy to get around KL. There's a monorail (above ground like the BTS in Bangkok) that goes around town so you can travel around pretty easily.
There's also a special tourist bus - forget what it's called, but it stops at various points around town and passes the main tourist sites (Sultan's Palace, Grand Mosque, KL towers and the Bird Park ... don't bother with that!) You can get off the bus to look at things and then get on another one as they run frequent services.

We stayed in the main part of town so just had to walk around the corner to the main shopping precinct. Our hotel was right across the road from one of the monorail stations so it was easy to get around town.
Our hotel was the Istana - highly recomnended.