Actually your Fort Liberty one is kinda nice. Somehow it works for me, even if the design is the same as the other two.

I have the exact same problem. I have the visual knack of a doorknob. But there's a couple of things I do to help crutch me up a bit:

1. I avoid primary colours. Like #ff000, #0000ff
2. I pick a sort of a colour theme and then everything else is variations on that, right down to the rollovers.
3. I look at phpBB themes for colour theme ideas.
4. If there is a nice pic the customer wants to use on the site, I'll pick colours out of it for the site.

So while I'll probably never win any graphic design awards, most customers wind up liking what I do for them.