Actually, it looks like I found time to do the map color testing today (took #&*! hours...)
After fiddling enough with the color settings to be sick and tired of them for life, I have found that in my opinion the following would make best color defaults (assuming Lintman's filters)
Plains: dcc8af (or possibly e1cdaf if you like a slight bit darker, but imo the first is better with the forest and mountain colors)
Swamp: 969687
Tundra: d7dce1
Wasteland: e6b464
Farmlands cdcd82
Forest: 466446 (or possibly 465f46, or perhaps 46644b, but the first one is imo best)
Mountains: 8c6455
Sea: afcde1 (I could test some more possibilities for this one)
Sea border: 0f417d (darker) or 2350a0 (lighter), depending on what you prefer. The ideal is probably somewhere in between, but it's half past midnight here, and my gf will kill me if I stay up any longer twiddling with this.
I like these colors more than the initial ones, because they are more powerful. A map with the same random seed (7) made with the earlier suggestions compared to one made with these new ones looks like a pale ghost with a storm-darkened sea.
The most difficult part was finding a proper swamp color, and it only cleared when I switched the old forest color to swamp and then leached some of the green away from it.
Run the program with these settings and compare to the old, you'll see how much better it is now.
Edi