I use the standard plugs from the stealership (unfortunately- stealerships is likely being too kind in the description). I change mine every 30k because it's what's called for in the manual and it won't void my extended warranty (lengthening the time between spark plug changes is seen as a lack of maintenance by Toyota). If you buy the plugs yourself and do the change yourself it's really easy and will take you less than an hour after you get the hang of it (if I'm really cooking I can do all of it in less than 45 min...). You'll need a 10inch wobble extension, a 4 inch extension, a ratchet, a torque wrench, a spark plug socket, various metric sockets (I think 8 and 10...), some anti-seize (aluminum block), a spark plug gapper, a rag (for the anti-seize mess), of course the plugs, and a wee bit of patience...

enjoy! it's really not as intimidating as it may seem at first...