A tailored French cuff shirt and a pair of designer jeans is also a popular way to wear a French cuff shirt (no tie of course).
You can wear them with a pair of straight legs, unbuttoning the top two buttons and either wearing them with links or with the sleeves rolled. If I were to wear it like this, I would probably wear a solid colored shirt in mercerized cotton.
French cuffs worn open with an athletic shirt underneath and a pair of loose fitting jeans will also work. For this look, a pair of white Air force ones and a big belt buckle would probably be best. I would probably wear a patterned woven shirt, maybe something with stripes and paisley inside the collar and cuffs.
I have definitely seen French cuff shirts become more of a casual fashion statement in the last few years. They are versatile shirts that look good any way you choose to wear them.