Compared with iDine, one mile per dollar isn't much and wouldn't likely motivate me too much. I think the quality of the food, service, etc are much more important.

The idea of loyalty tiers is interesting, though. Lots of places, especially family run ones, will often comp a drink or dessert to the regulars. Keeping better track of this might be a solid idea.

I think this might work best in an area where the food is less of a differentiator. Specifically, I'm thinking of a restaurant that caters to casual business lunch crowd. A deli, or something like that. If I can get pretty much the same sandwich anywhere, small perks could be the difference maker.