Give me a good game packaged in with the system like you did with Wii Sports and Super Mario.  Other than that I'm fine.  I already know the graphics and storage space will be improved upon.

1080p graphics

HDMI output

achievment/trophy like system

non retarded online gameplay

full BC with Wii and GC

A gratifying library of games, the ability to skip the menu and go straight to the game, and shorter loading times.

No, really. That's all I'll need.

This and only this. If it happens to accommodate 3rd parties better and lead to more support, that's great. If it doesn't, I'm sure it'll be totally innovative and worth it (again).

edit: oh! and obviously add the complete Dreamcast library to Virtual Console! how could I forget that?..

Dear Nintendo you always do things that might seem bad but in the end you make us want what we did not know we wanted so do your thing and this time I will just take it without doubting you one bit! Surprise me like you always do in the end! :D

I would want an HD. That's all I can think of for now.

Dead Nintendo: For the Wii 2 I want you to hold off release until late 2013 or early 2014.

For Nintendo's new hardware launch I want a WarioWare: Motion Plus game!!

Up until now nose-picking has always been a binary operation in the series (finger in, finger out) but with the power of motion plus you could have uncountably many ways to perform the interaction between digit and nostril!

Just think about it: different angles of entry, twisting the finger inside in various ways, distorting the nasal cavity, it opens up a whole new world of possibilities!

This must be made!!

here are some quick proofs of concept (not directly shown for benefit of  surprise factor)

(copied from a post I made elsewhere)

1. 3DS-style friend system

2. Modular main controller, something that can click around and be dual analogue or motion controls

3. Solid-state media (so i don't have to replace the disc drive on this thing either)

Dear Nintendo,

Please release the Wii 2 in time for Christmas with Super Mario Galaxy 3 and an HD version of Skyward Sword. But most important of all, make an HD remake of Metroid Prime PLEEEAAZE.