2 day Tokyo Metro pass

I'll be landing in Narita and going down to Kyoto, etc for 10 days before coming back to Tokyo. I see I can get a 2 day metro pass for 980yen, a lot less than separate one day passes. But can I buy these in Narita before leaving on that first day even if I'm not planning on using them for another fortnight or so? Is it like the JR Pass in that first use validates it and it's then good for 2 days?

But can I buy these in Narita before leaving on that first day even if I'm not planning on using them for another fortnight or so?

Yes.

Is it like the JR Pass in that first use validates it and it's then good for 2 days?

The Japan Rail Pass is not validated by first use. Instead, you specify a start date when exchanging the voucher.

The 2 day Tokyo Metro pass, however, is validated on first use.

Thanks again Uji. This should save me a lot of money

Actually, looking at it again, it appears that most of my travel is with the Yamanote loop which isn't covered by the Metro pass (as far as I can see), so this is irrelevant.

Looks like I'd be better off with the Tokunai pass for some days. Is that my only alternative, or am I missing something?

To make JR Tokunai Pass pay off, you need to use JR train 4 or 5 times a day. If you dont plan so, SUICA IC card is your option.

Mgal, where are you traveling to? Most places the Yamanote Line covers is also within range or also served by Tokyo Metro trains as well. I find the discounted Metro Passes purchased at the airport to be a pretty darn good discounted deal, especially the 2 day version.

To make JR Tokunai Pass pay off, you need to use JR train 4 or 5 times a day

That's a good point Ts, even the 2 day pass was pretty close to breaking even (ie total journey for 2 consecutive days topped at about 1100yen, so not a massive saving). None of my days go above 730yen at the moment.

Most places the Yamanote Line covers is also within range or also served by Tokyo Metro trains as well

I considered that once I found the Metro map online, but first off I'll be based in Shinagawa which is not on the Metro line, so I have to start each day by walking to a station or by some other means. On top of that, journeys become more complicated, taking in transfers and several different lines. I think I'll stick with the easiest (more expensive) route for my first visit :)