Mummabear--you could always MAKE marshmallows. It really isn't that difficult. Just sayin', a marshmallow desert is NOT a place I'd want to live!
As to s'mores--I think you need the flavors of chocolate, marshmallow, and graham cracker to have a true s'more. However, you could add to it--raspberry, peppermint--in some way (fresh raspberries? peppermint patty? flavored marshmallows? cinnamon grahams?) You can use any type of chocolate. You could dip a marshmallow into chocolate fondue and sprinkle it with graham cracker crumbs, or have a chocolate cupcake with marshmallow frosting and crumbs. Or use chocolate-covered graham crackers--on and on.
My family goes to a ranch every summer,and they have a bonfire a couple nights a week. They provide marshmallows for roasting. having gone there 20 years now, we bring our own chocolate and graham crackers, and are the envy of all!