At the bust station I decided to opt for one of the coaches operated by NICE which is a subsidiary of the Plusliner bus company. The Nice, or Nice Plus, ticket office and depot front right onto the road at KTM (you can't miss it) enabling the taxi to wait outside on the taxi rank. Their coaches carry fewer passengers and have more leg room for a slight price premium. The ticket costs RM 74 (one way) and takes 4 hrs 30 minutes. There is an onboard movie and they also serve a light snack (in my case it was a very tasty warmed roll containing what tasted like a savoury mince based on anchovies and a small doughnut with a cup of water) and coffee during the trip. You could take a regular Plusliner for RM50 but for me the extra leg room and better service is worth the extra RM 24. There is no toilet on the coach so pay a visit before you set off!!! Mid way through the journey the coach does stop off at a small service area where there are toilets etc and for a 10 minute leg stretch.
There is a good waiting lounge at the Nice office and you must be there at least 30 minutes before the coach departs and must be on board 10 minutes before departure. If you are late, they don't wait!!! The buses depart outside the front of the building from where you buy your ticket.
The journey from the hotel to KTM and back cost RM 33 and for me, as a recce, and being guaranteed a place on the coach, it was money well spent, at least at the time it was. Journey wise from most of the central hotels to the Old KTM will take about 15-20 minutes unless you are travelling in peak rush hour from say 7am to 9am. I suspect therefore that if catching an 11:00 am coach you could leave your hotel at 10:00 (they like you to be there 30 minutes before the coach leaves and board 10 minutes before when the steward/ess will check your ticket) by taxi, buy your ticket upstairs at Old KTM and await arroval of you coach. These coaches also travel to other destinations of course including Melaka, Johor Baru and Singapore.
The other main option for me to consider was Air Asia. This would take an hour and would have cost RM 142. The cost was not the issue for me but as I have said before I would rather see some of the country on the way out to Penang albeit I may well fly back. At the time of writing the cost of a flight back to KL 17 days from now is RM 50 plus about RM 30 for baggage.