I have discussed this before, and I know it will come up again. Marge Loch-Wouters over at Tiny Tips for Library Fun has a great post about the importance and viability of taking breaks from storytime. Take a look for some convincing suggestions that answer concerns you might have about taking breaks.
One of people's biggest concerns in taking breaks from storytime is that you might lose your audience, or that it is confusing to the patrons. Marge counters that with this:
If storytimes are to entertain, then fear of losing the audience might be real. If storytimes are to model and help provide parents with the early lit support they need to be their child's first teacher, it seems that breaks are easily incorporated since parents have the tools that you provided to keep modeling awesome early lit work with their kids!
She also suggests adding a transition activity (preschool dance party, creating some book bundles for families to check out, changing out felt board materials and other early literacy activities on the floor more frequently, etc.) to help ease people into a short do-it-yourself time.