pine bark mulch is the best all around mulch i've seen - its like "chips" instead of long light pieces and is really easy to top off later and is not colored and expensive like that dyed crap - and it makes a better barrier -
i've sold it to all my mulch customers lately and they ALL love it
* pine bark can be misleading on the package
*not the big chunks - check the label (bark might mean real bark)
*just the chips about the size of a quarter or smaller- some places name it differently so check before paying -
weed prevention included probably means preen - not bad but the mulch is probably not great
put down good mulch first and then buy separate preen granuals if desired and water it in or use rain