We are currently using ADP's RUN for four separate entities that are all managed through our central office. ADP made it simple to link all four accounts so that I can access all four entities from a single login. ADP allowed us to tailor our features (such as payroll processing, HR support, and 401k) for each entity based on its needs. The site itself is easy to use and has made processing payroll easier due to its simplified layout.
We did opt to include the HR support. This has allowed up to easily update our handbook (and will ensure the handbook stays up to date) and has provided numerous documents that have proven useful during performance reviews and onboarding.