Overseeding Grass Mix

I'm looking to do some aeration/oversedding jobs and need to know about the seed. Do you just use any type of mix or do you try and match with the type of grass your doing? I figured you should primarily seed the same type so the lawn looks uniform. So what do you guys do?
Thanks

 

For certain with cool season grasses I try to match what's already the predominant species being grown. I generally use a 80 / 20 or 70 / 30 blend of Bluegrass to Ryegrass. No fescue unless it's a shade area.

It's also helpful to use a few varieties of the species being grown to increase disease & drought tolerance.

 

That's kind of what I was thinking, but I'm not to good at identifying grass types. Is there a certian cool season grass blend that any one has had good results with for overseeding?