I think your plan for a pretty slate blue would be perfect. That way the steps and garage door don't need to be painted. The shingles are far enough from the porch & garage door that the "greyness" won't conflict with the tan in the shingles, and the slate blue would also match the roof shingles.

Not sure about poppy for the door, but the good thing about paint is that you can always paint over it! I mgiht go with a black or umber yellow, as they are close in color to the cedar shingles and the other colors you have.