There is no set answer. There are too many variables -- Age of blog? How much have you advertised it? What is your blog about? Is it optimized?
For some, 100 visitors a day seems great ; for others it is nothing. You also need to choose your hosting plan on the number of visitors to your site.
yes 100 is good but not great...no. of feed subscribers/readers,participating readers(comemnting), converting readers...etc are most factors...old blogs have good no. of visitors but new ones would be quite great with 100/day
Depends on the subject. 100 visitors a day may be amazing for a local businesses blog, but would be bubblegum change for a porn blog.