" I am also interested in chosing a better grass in case I finally
decide
to get rid of all fescue. I am very satisfied dwarf fescue, but the
wild
fescue makes me want to change to a different type. I am hoping that
there
is a type of nice-looking grass allows me to kill off all its
competiors and
grows well in my zone (Western Garden Book zone 14). "

With just about any kind of grass you choose to plant, their is always
the possibility of an unwanted weed type of grass showing up. A grass
like Zoysia is so dense it will virtually eliminate competition, but it
has it's own issues and isn't appropriate for many parts of the
country. The best defense is to encourage dense thick growth, which
will keep weeds and undesirable grass from getting established. If
it's just in a few areas, killing it and then reseeding is the best
option.

There are two other alternatives that you may want to consider. There
are now some tall fescues that have been breed to be glyphosate
tolerant. That means you can use Roundup, in the correct amount, to
spray areas that have the weed grass you want to kill. Used in the
correct amount, it will stunt the tall fescue somewhat, but not kill
it. I think this could be a solution if this has been a consistent
problem and/or you live in an area next to open fields, etc., from
which undesirable seeds can easily spread. To do that would require
killing/reseeding.

The other option is that there are chemicals, like Acclaim, that will
kill some of the coarse weed type grasses, but leave fescue intact.
What would be most helpful would be to get the grass identifed. To do
that, you generally need to let it grow to a seed head and take it to
an agrictural extension service. Without identifying it, you could try
Acclaim, but it's expensive, might not work, while there are other
chemicals that could be effective against it, if you are certain what
it is.