Well for example I like daisies and buttercups which are condidered weeds. The foliage is ok and the flowers last a long time.

There are lots of types of creeping thyme and it it can swamp out many types of weed. Some have pretty flowers but I'd go for one with pretty folliage as it never goes away. Shorter varieties are best as it covers easier. All smell nice when you step on it so is great if you put it in the cracks between paving stones.