Wii - add hdd
360 - add wifi
PS3 - remove blu-ray (keep cost low)

Wii: Earlier release date so I could have that sexy thing in my posession sooner.
PS3: New controller.
360: Quality checks.

Wii- Bundle with Legend of Zelda: Twilight Princess.
Playstation 3- A cost of 599 US dollars and Giant Enemy Crabs kinda lowers the appeal. Id say lower it by at least $100.
Xbox 360- Add in parts that prevent the console from Red-Ringing.

Wii: Release price of $1
Ps3: Release price of $1
360: Release price of $1

Wii - motionplus from day one
PS3 - HD-DVD instead of blu-ray (would allow for an earlier launch, lower price and potentially faster read speeds)
360 - more exclusive content

My choices for changes would be:

Wii: hardrive/ mass storage device built in

360: obviously stick with original release date and no rush release with major issues, bundled software outside of the holidays, smaller chipsets/cooler unit

ps3: bundled software;  I'd say lower price but frankly I wouldnt want to sacrifice anything in the unit aside from wifi ($10), faster optical speed would be nice but frankly I like installs and reduced pop-in by having installs (load times on non installs arent much better on 360 game versions), I would also argue for smaller chipsets and a cooler unit.

About suggested PS3 price reduction and hardware changes: they would not release 2 versions (1 with blu-ray and 1 without) because the main reason for the use of blu-ray was for game storage so split release would result in 2 game versions for 1 console and would cause more confusion than the BC dilema.  The reason for blu-rays insane cost at launch was from diode cost and lack of diode producers (diode alone was $50 and is now about 9x cheaper) without the shortage it would have been much cheaper at launch and the console supply wouldnt have been constrained.  Launch price was no big issue for me on any console but price reductions should have and could have been faster for both 360 and ps3.  Sony always has had a issue with this though.