The Monorail is the best way to get to Bukit Bintang as it is not directly served by the 2 existing LRT lines (an Bukit Bintang Central MRT station is under construction but will only start operating in 2016). KL Monorail is operated by Rapid KL which also operates the 2 LRT lines and a fleet of buses. At the the Hang Tuah station and Titiwangsa station you can transfer to the LRT station without having to buy a new ticket. The ticket (which is actually a token) can be purchased at ticketing machines at the station so have small notes and possibly coins ready. At the end of each direction the dual track turns into one track, which means the train goes in the station and then reverses out again. So you can actually stay in the train. This way you could use the Monorail as a little sight-seeing tour and only pay for one station ....

Operating Hours:
First Train: 6am
Last Train: 11.30pm (KL Sentral towards Titiwangsa)
                    11.50pm (from Titiwangsa to KL Sentral)

Fare:
The fare varies between RM1.20 and RM2.50, depending how long the ride is.
more information

Monorail in Bukit Bintang

Bukit Nanas station on top of Jalan Sultan Ismail

The Monorail gets really packed during rush hour (8am - 9am, 5pm - 7pm), avoid using the Monorail during that time if you carry big luggage

inside the Monorail

the Monorail track along Jalan Sultan Ismail, Bukit Bintang

Huang Tuah station, this station is a interchange with LRT Ampang Line
 

Map of all Public Transportation in Kuala Lumpur and Klang Valley (excluding buses) and beyond:


click image to open the PDF