You can add wiggly arpeggio lines to spread chords instantly, straight from the Keypad. They're attached to notes, so Sibelius automatically allows room for them, and they transpose with the notes too. Use a normal wiggly line, or one with an up- or down-pointing arrow.
You can also make ties break across time signatures, by being drawn behind them. In fact, you can make any object go in front of or behind any other, like in many drawing programs. This is particularly useful for putting imported graphics in front of or behind staves.
Articulations are automatically drawn inside or outside slurs or tuplets depending on the situation, with a host of subtle options. You can also reposition multiple articulations on the same note individually rather than all at once.