Ornamental and Fuctional Aspects in the Same Invention

My invention has both functional and ornamental aspects – can I file for both utility and design patent protection?

Absolutely.  Both aspects of the invention can be protected.  Some considerations (there will probably be others):

Timing: Ensure that both applications have the same filing date by submitting them at the same time.  It is easier to file them on the same day than to file them on different days, for legal and administrative reasons.

Provisional: Only a utility application benefit from an earlier-filed provisional application.  A design application cannot claim back to a provisional.  In other words, a provisional holds a spot in line for a non-provisional utility application, but not for a design application.  So again, consider the importance of timing.  Filing a provisional does not secure a filing date for eventual design patent rights, so disclosures made after a provisional is filed can be risky.  If you are going to file a provisional, file it on the same day as the design application.

Disclosure: Make sure that the scope of the design application and the utility application (whether provisional or non-provisional) are commensurate to each other.  While the design application is comprised of drawings showing ornamental parts of the invention and the utility application is comprised of description and drawings regarding the structure of the invention, the scope should be the same.  In other words, there should not be three embodiments in the design application that are not in the utility application, and vice versa.  You want to avoid dedicating anything to the public by disclosing it and not claiming it.