UV'ing / Texturing Complex Scene

Hello,

How can I UV / Texture a complicated scene with multiple objects to look as professional and AAA as possible?

I'm hoping to upload it to multiple places once complete such as sketchfab, cgtrader, turbosquid and eventually get it into Unity to display it in engine.

For understanding of the scope of this, it is essentially an environment piece, a launch pad for a rocket, a rocket, UFO's, a ticket booth, turnstiles, concrete platform with reinforced iron. I want to retain a lot of detail.

A past project of mine I did all the pieces separate and it was a bit of a pain (especially when adjusting anything) having 15x normal maps, Diffuse maps, specular maps, ambient maps, and emission. Is there a better way to go about things or is this just how it would be handled in a studio?

Any tips or advice would be appreciated.

Thanks,

Chris