I've had occasion to stay in many B&Bs over the past 5 years, most 3 rooms or less so I guess that's what you would term "Mom & Pop". They usually strike a pretty good balance between being accessible and leaving us alone.
As far as amenities and services go, we're low maintenance: good, nourishing breakfast served at a table; a different breakfast every day; queen bed, regular bath and/or shower. Good, large, thick towels. Don't need a tv, as long as they can tell me what to expect of the weather. Don't need evening turn down, but do want someone to make up the room in the morning. Don't need wine, chocolate dipped strawberries, etc. but do appreciate a natural soap and shampoo, and the owner having a stash for emergencies (i.e. toothbrush and the like).
Prices vary, but we'll spend more money for the following: space (a king instead of queen bed; a double-sized bath and/or shower; a private balcony or porch). Access to equipment (e.g. canoes, bicycles, BBQ). A picnic service. Shuttle service. And, as catlady mentioned above, the innkeeper's attitude encourages return visits!.