Appropriate solution in this case is to create your own Site Families and use them. For this you need first create necessary Site Families in Server -> Site Families section. After that go into Plan management section, select appropriate plan, disable default Site Families and enable your own which you wish to use.
Actually, it is possible to update Title and Description for default Site Families. Title can be updated in sitebuilder3.site_familia table and description in
SITEBUILDER_ROOT/resources/locale/en_US/Wizard/Start.lng:
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familiaTitleBlog = "Create your blog"
familiaTitleGeneric = "Create your site"
familiaTitlePhotogallery = "Create your photogallery"
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But it is better not make any modification in database and use first way which I suggested.