Good advice so far, once the "active" phase of fermentation is done the airlock should have very little activity so leaving liquid (vodka, star san, water, etc..) will be fine. I have had (I use cheap Tequila) my airlock bubble for 3 weeks and the alcohol is still in it.
Come to think of it, I wonder if I am having a problem with my beer since I have never had a beer "off gas" for 3 weeks before. Oh well, time will tell!
One of the hardest things about brewing I have learned is patience! Time does tend to heal most wounds in brewing.