No sugar or sweetener is going to have any remnance of vitamins & minerals, with one exception - blackstrap molasses.. Sorry to disappoint, but sugar is sugar. And a gram of sugar is going to be 4 calories. (since sugar is 100% carbohydrate and 1g of carbohydrate has 4 calories)
Sucanat is a brand name but is basically brown sugar. I think it has more molasses than typical brown sugar, but it's pretty close.
Turbinado is the same as Demarara and is like a light brown sugar.
Molasses is sugar syrup. Boiled cane (or beet) juice, basically. (a bit more extensive than that, but that's pretty much the idea) Blackstrap molasses has a lot of iron & calcium in it.
Brown sugar differs form white sugar in that it has slightly more molasses in it. Some brown sugars are made by adding molasses to white sugar; others are made by simply less refining.
Splenda is a brand name for sucralose and is an artificial sweetener made by chemically altering sucrose (glucose + fructose).http://en.wikipedia.org/wiki/Sucralose
There are a lot of other sweeteners out there, including high fructose corn syrup which is basically corn syrup that has been altered to contain a higher % of fructose to increase sweetness. But really the take-away message is that it's still all sugar. Brown sugar isn't any "healthier" than white sugar, and blackstrap molasses is the only sweetener that has any trace of nutrients. But, honestly, if you want calcium or iron you're better off cooking up some collards in a cast iron skillet and serving them over some spicy lentils with a bit of tahini & lemon juice.