with the casual nature of the zippered boot, i think you've gotta do metal eyelets. "sleek" is not the point of a zippered combat boot.
edit: i do see that all the margiela zippered boots on yoox have blind eyelets. feels weird to me, but ok.
a friend who was moving gave me his black leather cons. So i put leather laces in and painted them.
I like the effect on the black leather more than the white canvas version i tried last year. the laces are too short, but they were what i had on hand at the time, and now they are painted into place anyway.