The island of O'ahu can be generalized as a rocky volcanic island. However, it covers almost 600 square miles, and has varying geography in different parts of the island. The simple conclusion is that there is no one magic terrain, flora, or rock controller that accurately portrays all real life characteristics of all parts of the island in the game, all at the same time. The best I can do is download as many (non-conflicting) plugins (and tweak them) such that the underlying terrain is acceptable, and pick flora that looks close enough to what may be found in the corresponding area in real life.
Generally, I would generally classify the dirt of the island into three areas. The southeastern part of the island has darker brown dirt. Most of the island, from 'Ewa to Kahuku, has famously reddish dirt (good for farming). The northwestern part of the island has faded to light brown dirt. This is the result of the Wai'anae Mountains being older than the Ko'olau Mountains, and the differring geography leading to different decomposition of Hawaiian basalt.
I've chosen the Red Granite rock mod by pegasus. Up close it's somewhat red, and far away it looks brown.
As for terrain, I've chosen hemblem's Californian Terrain Mod. It's green at low elevations, drier at "mid" elevations (good for highlands), and then pale green at the highest elevations possible on O'ahu (+1100m above sea level). I've also modified the plugin so that beaches extend "forever" (at elevations lower than 251m) so that I can make variable width sandy areas.
I cannot represent the windward-leeward look with a terrain mod because the terrain mods depend on elevation, not with rain patterns. Flora is how I plan to mimic the windward-leeward difference.
I'm in awe of natural environment shots I've seen in other people's work. I've downloaded many ploppable flora plugins available on the STEX and LEX. The following is the result of about a week of playing around with mayor mode ploppable flora, rocks, and water.
Although Pearl Harbor is thought of as the quintessential U.S. naval base, and today it is virtually surrounded by suburban development, it once was a huge wetland area. There are still small pockets of protected and undeveloped shoreline. I've chosen two such areas on both sides of the Pearl City peninsula.
I'm not sure what the first area is exactly. Google and maps I've seen doesn't have a label on it. It's a grassy area between the H-1 Freeway and Pearl Harbor to the west of the Waiau Power Plant in Pearl City.
Here is the result of my interpretation of the area in the game:
The second area I've chosen is known as the Waiawa unit of the Pearl Harbor National Wildlife Refuge. The refuge is actually only the two ponds (with greenish looking water). The wider area is owned by the U.S. military.
I've started by "roping off" the area with roads. This is to restrict the area that I'm considering.
I put in the small stream that runs through the area, and the larger dirt tracks/abandoned roadways as reference points in the game. I also refine the look of the shoreline.
After many (discontiguous) hours later, the flora, rocks, and ponds are put in.
The zoom 1 picture of the area.
On Monday, I'll be starting yet another semester, and I know I won't have as much free time as I'd like. For the next update, it'll probably be more protected areas/undeveloped land. I'm not sure exactly where, but it'll probably be on hilly, if not mountanous, terrain.