This is a very similar to the planting scheme that Geoff Hamilton used to use in Gardeners' World many years ago when he planted alpines in the gaps between paving slabs in a patio. I'm using block paving because it is cheaper and also easier to make into curves.
I have one plant in a gap so far, and I'm growing a whole lot of mixed alpines from a seed packet from Chiltern Seeds. I'm hoping to fill in lots and lots of little holes with these mixed alpines, so that in the end the bricks are almost entirely obscured. This is an exercise in cheap-skate, low maintenance gardening!