Mithras said:
How do I make these unique, interesting and alien?
I've done the hyper-polluted Bladerunner style world, the 'world-city' Corsuscant type world and the Megacity One surrounded by irradiated wilderness type world.
What else?
Azun is a good suggestion -huge archeologies, separated by open land.
Another consideration is to take the planet size into account. A siz A one will have more surface room than a Siz 5 (the mean); it may similalry have less wreckage (ala Bladerunner) and less urbanized cities simply due to more room.
A huge very high tech hi population could spread out much more if resources were easily available and distributed. Could be much more of a Jane Austin Britain type planet.
Japan, as I suggested, is another idea. Very dense population, very structured culture and society -and no megacity radlands or bladerunner pollution (?), either.
The thing is, the main cause of the grittyworlds is too much crowding for resources (yes, duh); but resources are partly a function of technology - if the population has an approximately equal chance of getting what they need, (which includes employement), one can see a dispersed very high population planet; it would require extreme advances in (among other things)food production, resource distribution and waste disposal, as well as decentralized local production...but hey. This is a sci fi setting.
And when the UPP suggests a garden world, how do you stop these looking like Earth or like a Star Trek set?
Low pop worlds, I have no problem, my worlds are alien, challenging and different....
Easy. A garden world just needs a good ATM, water and a good temp. For traveller, all one needs is enough water and breathable atmo.
The coasts of the antarctic certainly count as garden (water plus air), as do the deepest of the equatorial jungles (assume the congo or the amazon for water); one could argue that Utah around the salt lake does, also.
The post cambrian/semi-devonian earth would count, too, depending on when the oxygen switch occurred -one could have no life worth mentioning on the land, and still have enough O2 to count from the sealife.
Similarly, the post dinokiller asteroid world probably still counted as garden even with mass climate disruption, vast ecological destruction and toxic decay products everywhere, possibly firestorms everwhere or complete sunlight loss (or both) but....enough O2 and water.
Finally, consider that megacity one earth might well count as a garden world - atm normal, no taint (apparently, noone wears breathers or resperators full time), Water code 7 (polluted, yes, but that isn't part of the ATM code).
Don't get hung up on the garden part....barely tolerable (as opposed to habitable) places can be garden worlds -just compare them to(say) Venus or the moon.