Salt ratios

I understand some people like/need more or less salt, but I get frustrated with recipes that only say salt "to taste." Does anyone know of basic ratios of salt when cooking for the average palette/diet? I'm especially interested in a salt ratio for potatoes. Last night I made potatoes au gratin dauphinoise for company. In guessing how much salt to use, I ended up being too cautious and they had basically NO taste. Starting with potatoes, then going on to other meats and vegetables, what are some good guidelines for adding the right amount of salt to recipes? Thanks.