It is popular these days to have drapery panels touch the floor when installed.  Shown above are three different examples.  The first picture shows what we call a "break" which is 1-2" on the floor.  The second picture shows about 3-4" on the floor and the third picture shows what we call "puddling" which shows about 5-6" on the floor.  Choose your length based on personal preference and lifestyle.