If your objective is to see as much of the country you're visiting, then you'll need to travel considerable distances. It so happens that Malaysia has an excellent railway system, called KTMB. The train in Malaysia is efficient, comfortable, as well as family and tourism-friendly. Best of all, the vistas out of your window are gorgeous. And to top it off, train tickets are downright cheap.
But as if all that isn't enough reason to opt for the train, you'll find that seating on the train is rather comfortable; most seats are of the Pullman variety, i.e. they're roomy and can recline back a fair ways. Naturally, the carriage interiors are fully climate-controlled.
The forward-thinking KTMB has also made all journeys bookable online. So if you want to reserve your seats now, just use below forms. Have a great trip :)
Pro Tip: Use this reservation form for train routes in Thailand, Singapore as well as of course Malaysia.