The commonest means of getting to and from KLIA and KLIA2 airports and the City are as follows:
The Airport Coach
This costs just RM10 for a one way ticket between KLIA to KL Sentral and RM18 for a return ticket. The cost is the same if departing from KL Sentral to KLIA.
The price is RM18 for a one way ticket from KLIA to hotels in the city and RM25 from hotels in the city to KLIA.
The buses run every 30 minutes from 05.30 to 00.30. More information can be found on their website:
The KLIA Ekspres Train
The one way ticket price from KL Sentral to KLIA or vice versa is RM55 for adults and RM25 for children aged 2 - 12 years. Special Offers are available if you purchase a ticket online. The journey time is just 28 minutes between KL Sentral and KLIA, and 33 minutes if you are traveling from KLIA2. The train schedules can be found on the following link:
The only negative about taking the KLIA Expres is that once you arrived at KL Sentral, you may need to transfer to an LRT Train or bus to continue your onward journey or take a Taxi from outside the building. There is a taxi counter in the building but it does sometimes have queues.
There is a counter at both KLIA & KLIA2 after passing through Immigration and Customs where you can buy a Taxi Voucher. The cost varies a little depending on which part of KL you wish to go to. It is in the order of RM70 to get to Bangsar by Budget Taxi (usually the car is a Proton Waja), and about Rm102 by Premier Taxi (usually a larger car like a Nissan or Perdana or MPV). The Counter usually accepts payment by cash or credit card, and if they are not accepting credit card when you are there then there are ATM's just outside.
You can also get a metered taxi from KLIA2 and will be asked to pay the toll road charges. The fare may be as low as RM65 but usually around RM70 or a little more. You can take a normal metered taxi from the city to the Airport and the normal meter charge will be about the same, somewhere between RM65 and RM75 or thereabouts. If a taxi driver offers to take you there for more than this then I'd walk away.
When you exit from Immigration and Customs you will probably be approached by men offering you a taxi to the city. These are the so-called "illegal" taxis. The rate may be reasonable or terribly high, but you will be taking a risk, one that I would never take. Stories in the past about those kinds of taxis stopping for petrol and the drivers buddies suddenly jumping into the taxi are scary. Anyway, I would recommend taking an official taxi rather than one of these.
I will usually take an official taxi from the airport to the city. But I always book from the company Airport Limo when traveling from the city to the Airport. The charge is around RM70 for their Budget Service and RM95 for their Premier Service. I have taken their Luxury Service a few times as the have Mercedes E cars in their fleet, and think I paid around Rm200 or thereabouts. I keep their number in my mobile phone, but you can take a look at their website:
Bear in mind that if you book a taxi between midnight and early morning there will be a midnight charge.
In summary, if you are on a tight budget, then take a coach as it is the cheapest way to travel ether alone or with family or friends. If you are a single traveler and want to get to KL Sentral quickly then take the KLIA Ekspres train, but consider that you will may then need additional transportation to your final destination.
But if you are a couple or family, then the most sensible and cost effective would be to use a taxi by buying a taxi voucher at the official desk in the airport. For me, there is nothing worse that having to cart heavy luggage with family members from a train or coach to a taxi stand or bus terminal when for a few ringgit more you could get a cab from the airport directly to your home or hotel.