You can put week block under the sand or gravel base to keep plants at
bay. Anything that does grow is easy to pull.
I don't anticipate any serious ongoing maintenance problems after the
pavers are installed. One of my long-time friends who lives in Old Town,
Alexandria, has a house built just after the Civil War that features a
brick patio put in at the same time the house was built. The patio is
brick on sand. It still looks good. Once in a while he gets a little
moss between some of the joints. The moss just adds to the character of
the patio.