What features do P-I-E languages have in common?

Okay, my goal is to design a family of languages that all descend
from PIE, but have been completely isolated from all other
members of that family for the past few tens of millennia
(give or take whatever it takes for there to have already been
a PIE at the beginning of the isolation.  I'm typing without
my references here. :)).

So, my question: apart from the common vocabulary roots, are there
any grammatical tendencies that are present more often in PIE
languages than in non-PIE languages?  For instance, are most
PIE languages inflecting, or specifically tail-inflecting,
or whatever?  Or is the common set of roots the only family
resemblance?

-Mark

Replies