I'd encourage anyone who is considering a d20 space opera campaign to wait until the Traveller d20 comes out before deciding. Traveller is classic space opera, and past versions of the game have been very flexible.
We ran an "Aliens" style campaign with Traveller once, in which the characters were Imperial Marines searching out nests of Aliens-type creatures before the infestation could spread.
We once ran a purely trade-driven campaign in which the characters were building a fleet of far traders and establishing new trade routes.
We ran an exploration campaign in unknown space -- or at least parts of space for which the information had become lost. We were really rediscovering lost colonies on long-forgotten worlds.
We ran a pirates campaign, raiding ships and settlements.
We ran a campaign in which the players were members of a rock band traveling around, performing on various planets. But the players also were spies, disguised as a rock band, trying to uncover plans for a revolution against the empire.
Point is, Traveller is set up to handle just about anything you want to do. It can even handle a Fading Suns/Dune-type campaign.