I went through several ideas, including going for the "split" paint scheme (think the Angels Sanguine or Storm Lords), but as that would be very difficult and didn't quite fit with the fluff, I had another idea. This idea ties into the whole Graeco-Roman theme behind the army. While in temperament they would be somewhat closer to Athenians (interest in philosophy, art, and leading the population), Space Marines are, by nature, very Spartan. Not to mention the fact that the color worn by Spartan hoplites was a good, deep red, and Blood Angels are red. . .well, it just makes sense. Anyway, the predominant scheme for the army would be this:
I use Mechrite Red as the primary color, as it's darker than Blood Red and also goes on more easily. The lower half of the leg and also the helmet are Dwarf Bronze. The thought here is that the bronze legs and helmet represent the bronze greaves an helmet of a spartan hoplite. As poorer hoplites could not even afford armor and simply went into battle with a shield, the scouts will be all red. Then we have your basic marine with the above scheme, to represent a slightly wealthier hoplite who could at least afford basic armor. Next we have the sergeant/veteran scheme. . .
The added bronze on the shoulder pads and chest plate are to represent the wealthier (and perhaps more successful) hoplites who could afford a bronze breastplate. Also, for the sergeants, I plan on using a transverse (sideways) crest. Believe it or not, that kind of crest is a pain in the butt to track down. The only one I've found so far is the one on the Cato Sicarius model, and that will involve filing off the Ultramarines "U", which will be fun. Obviously, Sanguinary Guard, as they have the fully molded armor (which is very Graeco-Roman!) would be entirely bronze, as well as most of the characters. I've also found the perfect shields for terminators and veterans or characters, at Scibor Monstrous Miniatures. Check 'em out! One even has a very Imperial-looking purity seal-ish thing.
The one debate currently raging in my head is this -- should I paint the left shoulder pad bronze to represent the typical hoplite shield? It would be very fluffy, I'm just not sure if it fits entirely. Here's what it would look like. . .
As I said, it would definitely fit the army theme very well, I'm just not 100% sure it looks good from a painting perspective. Anyway, I'm pretty stoked about figuring out a unique paint scheme. While many chapters have the lower leg/helmet areas in a different color, I haven't seen an army mix a metallic and non-metallic in quite this fashion. In fact, outside of Grey Knights, you don't see many metallic marine armies at all.
Oh, and lastly, all of the images were provided by the great Space Marine Painter Tool you can use from Bolter & Chainsword.