You might want to also ask them to bring a resume and headshot along.  Be sure, too, to specifiy what time of monologue you want (dramatic/comedic/classic/comtemporary) and length.

Ok an audition in a public location with customers coming and going?   If I'm understanding this correctly then this is not very considerate towards the auditioners.   And do you really need to give each auditioner a 1/2 hour to determine if they're right or not.  Way too much time devoted to each person.  So if you have 20 people audition that's 10 hours!!! 

And as a personal preferance I don't like private auditions or auditions closed to other auditioners.

I am a new director, but I just held audtions and felt they went fairly well. I am also an actor and know what I like at audtions. If you want a lot of people to show up, you hold an open call with requirements. Such as, be prepared to sing, dance, ect. It really depends on what kind of people you are trying to attract. It almost sounds like you are looking for professional types rather than community theatre people. Most non professionals do not have headshots, monologues, or songs prepared. Professionals do. If you are willing to teach a song or have them move regardless, that is quite different. Since it is a musical your first order should be to see if they can sing. If there is dancing and movement, this should be held as a group audtion to see how well they pick up steps or if they have experience. Having sides prepared is essential for non professional work. Monologues are ok, but can be extremely tedious, and time consuming. Having a song prepared is ok, but I think you will attract more people if you have an accompanist and some familiar show tunes. Also, do you have time for callbacks? Just my thoughts.

max

I beg to differ ... I live in a very small town (less than 500), and the fewest we've had turn out for an audition is 20 kids.  For those who don't have something prepared I always have sides available, but it's often painful to watch them try and read, so I'll often have them recite poetry or tell a story.

I dislike private auditions because I only get to see what that one person is doing.  I like to see how they interact with other potential cast members.  I have seen instances where a person one on one does very well however they do not mesh as well as someone else.  I realy need to see them reading with someone else.  I want married characters to work well together.