Pulling weeds takes a little more effort but I find it works better then vinegar at getting to the root of the problem. Replace the weeds with ornamental weeds to your liking, then a few sheets of the Washington Post (they use a non-toxic vegetable ink) are added between the soil and any mulch you lay down.
Store brand vinegar is typically 5% acetic acid. You might try adding acidic acid to increase the acidity. Vinegar Weed Killer: http://www.garden-counselor-lawn-care.com/vinegar-weed-killer.html