We are on a flat lot and the first floor is set 10 inches above which is good for one step up from garage but looks a little squat.
I prefer somewhere around 30 inches above grade for first floor. Low enough that you wouldn't need a railing on a porch if you didn't want one. High enough that siding is away from the dirt, less excavating for a basement, and good size basement windows even without window wells. Of course there are no truly flat lots, you might have more slope than you think, and there will be some fill so that the finish grade directs water away from your house.
I like 3 steps :)
I prefer no steps.
ours will be 22 inches above grade (slab foundation)
(dirtwork should begin next week!)
our lot is also essentially flat and slightly higher than surrounding lots (almost 4 acres of coastal prairie)