world scenery addons

I wondered if anyone could recommend an addon that would improve the general scenery of the whole world, or at least a couple of continents. The majority of my flying is done (through cargo pilot) in short haul night flights, so it dosent need to be spectacular. I know that Just Flight has a few: FS scene, FS global (improves mesh terrain), Roads and Rivers of Europe. Are these any good and will they interfere with my current scenery addons (all the must haves from Liono's list, british airports e and se england.)?
I also wondered if there were was any freeware mesh terrain improver.
Thanks for you help.
Mossy.