It's actually East Railay chelle(unless you're talking about riding all the way around the penninsula...which is less-than-not-so-great to hellish 50% of the time)..... Thats another way to go....but for sure more money and you still need to get to Ton Sai via another longtail or walking over that "path" between West Railay and TonSai....a real pain in the ass with a big pack in 90 degree weather... and don't forget about the fight through the euro-hordes on Railay.
For first timers the Ao Nang route is best unless you're loaded and can afford a chopper. The ride on the Song Taew from Krabi to Ao Nang is super scenic and a cultural experience not to be missed....throw your pack on the top and hang on to the back like the trash man did when you were a kid...superfun!
Chelle is right about picking up snacks and stuff in Krabi....do it....you'll pay a premium on Ton Sai as it is only accessible by boat. Unless you really want a new one....there are guide books floating around everywhere....so save your money.
If you are in to deep water soloing (for a break from the over-run routes)....check out Matt Maddaloni's guide....
http://www.mattmaddaloni.com/Expeditions%20folders/Thailand%202004/Thailand%202004%20article.htm
There is also a great over-the-water slack line location down near princess cave on Phranang beach....ask around....
Have fun.
I spent nearly a year there....this is the fastest and cheapest way I know of....Take plane to Bangkok(~700$ on EVA airways from Seattle)....take AC bus to Krabi from Khao San Road(~200Bhat)...from Krabi take Song Taew(small white pick-up truck) to Ao Nang(20 Bhat)....from Ao Nang take long-tail boat to Ton Sai(50 Bhat). Stay at either Andaman or Dream Valley(150-300 Bhat per night depends on season). There are heaps of folks to climb with....don't worry about finding partners. Take 15 Draws and a 60m rope and shit-loads of quality chalk. Tsunami problems are non-existant now(sounds like a new ad campaign, Thailand...Tsunami problems are non-existant now!). Enjoy.
Thompson Rivers University in Kamloops BC has an Adventure tourism program in partnership with the ACMG.....check it out. You can climb and go to school!
http://www.tru.ca/tourism/advpgms/index.htm
Wild Country Zeros #4,5 and 6 available for the discriminating small crack enthusiast. Good condition. ROUGHLY corresponds to Yellow, Green and Blue Aliens. 100$ usd o.b.o..