Reason is no Sonar, but Propellerheads really struck gold with their song blocks feature they introduced a few versions ago. I would absolutely love to see this type of feature in Sonar! The user can define song blocks (for example, verse, chorus, bridge, and so on), record the music for each block, and then assemble the blocks into a complete song structure. Additionally, you can change or add to an individual instance of a block, so you could, for example, have the second verse of your song vary from the first verse.
This feature would be a huge benefit to songwriters and would overall add a new level of power and flexibility to the Sonar workflow.