Is there any way to have a custom label generator? This seems to sometimes work better, but can be temperamental.
ListLinePlot[Table[{x, 2 Sin[x] + x}, {x, 0, 50, 1}],
LabelingFunction -> (Placed[#1[[1]], Tooltip] &),
PlotHighlighting -> "Crosshairs"]
ListLinePlot[Table[{x, 2 Sin[x] + x}, {x, 0, 50, 1}], Mesh -> All,
LabelingFunction -> (Placed[#1[[1]], Tooltip] &),
PlotHighlighting -> "XYDroplines"]