(Galactic Readiness 100% all around, what do i get?)

Your chances to get the best ending r good I guess?

Galactic Readiness is basically a bonus for getting War Assets faster. 100% just gives you double the assets when you get them in the single player. It is possible to achieve the best ending without ever changing your Readiness.Do not forget that everyday you don't play the multiplayer it degrades 1% per day.

The Galactic Readiness percentage is applied to the War Assets you acquire. If its at 50% and you've obtained 1000 War Assets, then for the final battle you only have 500. So, at 100% all of your collected War Assets count.

I haven't played the campaign yet, but it also does affect multiplayer. When at 100% readiness, you get a 5% bonus to experience.

Your "Effective Military Strength" and what choice you made at the very end of Mass Effect 2 is all that matters in deciding what ending you get. Effective military strength is your War Assets multiplied by your Galactic Readiness, so for example, I have 7100 War Assets and my Galactic Readiness is 72%, so my Effective Military strength is 5112. There are sixteen endings, eight for each decision from the end of Mass Effect 2, and which of those eight you receive depends on your Effective Military Strength. Over 5000 gives you the best ending.

of course if you decide to play this game again in another year or 2 you will NEVER get a 100% or a chance at one of the "better" endings cause almost no one will probably be playing the multi-player. Kinda screws my plan since i figured in another year or 2 i'd play all 3 games through out of nostalga. Everyone will be grinding halo 4 or the new cod or borderlands 2.....

A cookie?

You get an Achievement. And what everyone else says pretty much.

But you don't need 100% for everything. Anything over 4000 is honestly good.

The Achievement you get for having 100%

Does galactic readiness change the campaign at all?

If you choose the "bad" ending then you get an extra 1.5 seconds of cgi ending.. If you pick the "better" endings it dont matter at all......

I haven't played ME3 multiplayer yet - too engrossed in the campaign. But when I'm away from my 360 or my son is hogging the TV :D , I often play the ME3 Datapad and Infiltrator games on my iPhone. They can increase your galactic readiness, too.

I don't know how fast they are at increasing readiness compared to playing multiplayer, but at least you have some chance to increase your readiness if everyone has moved onto the next CoD or whatever. And I'm sure there'll be some of us still around - I don't care about deathmatch-y online games, but I'm more likely to play a co-op game like ME3's multiplayer :)