Bark is softer underfoot than gravel, and less likely to tread into the house, but does blow around after the local blackbirds have rearranged it. Bark is available in various grades, from coarse to very fine to suit different applications.

Cocoa shell stays put once it's got wet, and has a lovely chocolatey smell but the downside is that dogs will guzzle it and poison themselves. So only for gardens without dogs.

See bark mulches at:

Rolawn, B and Q and Wickes

See coco shell mulches at:

Crocus

See bark comparison guide at:

Rolawn

See how to apply bark at:

Rolawn

This page has links to grades of bark mulch, cocoa shell, bark mulch comparison guide, how to apply bark, from Rolawn, Crocus