Blame Chart

[ndarville]

I think there has to be something “above” the chart for easy reading, so (2) is out of the picture.

[ndarville]

Check out the time-series chart.

[ndarville]

var groupName = 'group',
    groupColors = {'R': 'red', 'D', 'blue'};

var presidents = [
    { 'name': 'Clinton',  'group': 'D', 'period': ['1992-02-11','2000-02-11'] },
    { 'name': 'Bush Jr.', 'group': 'R', 'period': ['2000-02-11','2008-02-11'] },
    { 'name': 'Obama',    'group': 'D', 'period': ['1992-02-11','2000-02-11'] }
];

[ndarville]

Rendered obsolete by party-trend as far as I am concerned.

[ndarville]

This means the third (3) option was chosen—which I think is the best anyway. No native support for the kind of named labelling as displayed, but you could look into implement it on an individual basis.

[ndarville]

• [ ] Consider the option of overlapping periods as seen in the example.

[ndarville]

Look into what happens when periods overlap; may not neat something extra for this.