I think another Celtic vs. Grid kind of thing would be more interesting. That was really climactic (Or however you spell it) If it involved one type of weapon throughout only one fight that would only show that they are biased towards that weapon, that's what I think, anyway.
I think that watching a Pred go all out on an Alien would be cool. All weapons, all skills, versus one of those Grid types of Aliens, the REALLY bad ass ones that deserve rigid edged heads. That is the determination of how long an Alien has been around, right?