if you go tile, you need a good sub surface that will account for the expansion/contraction. other wise the tile will just crack. the shows always use some orange stuff they roll out then put the tile on it. you can use concrete patch to fill the joints, but don't think for a minute that it will never crack. usually after the first year it has let go.

Thank you both for responding. We bought two different types of paver base, and Yardvaark is right - the one is definitely ugly while the other (Quickcrete) is okay. The Quickrete does have a warning about silica, so I wondered if it is okay to leave it exposed or use only UNDER pavers? The buckets of stone dust is a great idea, as we definitely don't need a load of the stuff.

I have a paving stone path and you're right-- the weeds are so hard to deal with. joints make proper pulling tough and who has the time for that anyway? personally I love the look of moss but it does not choke the weeds out well enough. roundup is really bad for bees, and from the research I did on it, it doesn't prevent new weed growth, it just kills the existing ones (people correct me if I'm wrong). on my sidewalk joints, I've had luck killing weeds with strong vinegar mixed with a small amount of salt and a touch of dish soap. not grocery store vinegar, but 20% - 30% strength, put in a gallon pump spray bottle. I weed whack first and then fry what's left. it seems to help for about 1 or two months, sometimes longer for certain areas of my sidewalk. I haven't tried it on my stone path though, I'm worried it'll kill the pretty moss. unfortunately, weed control is never easy. I've looked and looked for a solution that's super long lasting and not horrible for bees, but it's just not really a thing.

Duplicate post: https://www.gardenweb.com/discussions/6102719/help-filling-in-cobble-stone-paver-joints#n=2