I think royal blue with plenty of silver accents - or those two with white as a third color (think 60% blue, 30% white, 10% silver) would be smashing! Gorgeous gelding! You could also reverse the proportions in any way you saw fit. For example, 60% silver, 30% blue, 10% white. Just my opinion. This would also be good with red instead of blue, but keeping the silver, or keeping the silver and white if you were going with three colors.
What colors do you like to see on other horse and rider combos?