Just read another thread about Vital Strike, and I came to wonder:
Why not make Vital Strike "activate" on a Move action?
First I thought about using a Swift Action, but this might be to powerful regarding high level full attacks.
I would definitely remove the option to Vital Strike on the move, but it would finally clarify the whole s!$! about it.
A move action is still kinda big to sacrifice so maybe the three VS feats should probably merged into one single feat.
EDIT:
OR, as an alternative way:
You activate it as a swift action, but the additional damage only adds to your FIRST attack this round.
How about that?