I've got the 3 speeders painted with a base coat (actually the first thing I used my airbrush on). All of the trimming (eagles etc.) are going to be dhenab stone with bolt gun metal doing the shoulder trim on the left pauldron. . .
The right pauldron is going to be coloured in variable colours to mark the company the marine is from. This will also be useful to mark squads. I think my 'force' will just happen to be made up of biker marines from 3 seperate chapters. The command squad will of course be from the 1st company as per the fluff. The little bits of colour also make it look more visually appealing with a bit of diversity between models (I really like the different helm colours the blood angels employ).
It was a big hurdle to start on these (as starting painting projects is for me) but now that I'm on my way I think I'll have them nearing completion by next weekend.