The standard regulator needs an input and output capacitor for operational stability. A 10uF tantulem on both sides usually suffices. These caps usually must be placed within 1 inch (2.54mm) of the regulator pins, otherwise track inductance introduces instability and oscillations.

As mentioned, power track width is important, as well as ground planes, but more important than ground planes is the current flow directions - here sometimes a ground plane can be more obstructional than usefull, especially on mixed signal pcbs (logic and analogue mixed).

For ICs placed far from the regulator put another 'bulk' capacitor, tantulem or electrolytic. These will help with 'heavy' current demands, and ~100nF caps close to the ICs as possible, for logic switching current demand by an IC.

Although the 'L' version might be OK for average current demand, you might find that you've underated the regulator for 'peak' (logic switching) demands, and might have to uprgrade to the TO220 package.