Hi Jim,
just to comment and for the records, SAP Business One 9.0 is out of mainstream maintenance as well. Hence I'd rather recommend upgrading to 9.1 or even 9.2 version directly, at same effort.
Please check
- SAP note 528296 - General Overview Note for SAP Business One Releases and Related Products
- The Upgrade Strategy doc for an overview of upgrade options/paths
Best, Peter