Can you recommend a dwarf variety of Nandina that is not invasive? Are the berries on a dwarf Harbor Belle variety poisonios to the Cedar Waxwings. Is there a Ninebark that is small in size appropriate for a small front yard garden?
You may want to look at the publication from Clemson on nandina. There are some Cultivars that do not produce flowers or fruit or rarely flowers or sets fruit. If the plant does produce fruit, clip off the berries.
See the publication for toxicity and birds. 'Harbor Belle' produces abundant fruit and not recommended. http://www.clemson.edu/extension/hgic/plants/pdf/hgic1071.pdf
Ninebark - Contact some local nurseries to see if there are cultivars cultivars they can recommend based on the mature height and width of the plant for your site.