PPro is a great complement to AE. It is actually an integral part of my workflow and most professionals. Here are ways with which you can/should integrate PPro into your AE workflow.
1) As an NLE, PPro has a great playback engine. Render work-in-progress from AE and use PPro to compile the work-in-progress renders. As your PPro Timeline gets propagated with AE renders, you will be better able to view your work —realtime playback. Then when changes are in order, you can more easily identify these areas in PPro and then re-render just the problem segment in AE.
2) You can edit footage in PPro and apply markers and simply copy from PPro onto an AE Composition. This is a great feature that no other NLE allows.
3) Then there's Dynamic Linking between AE and PPro which allows you to link Compositions/Sequences between the two apps and have changes in one app update in the other, immediately. This is another feature that exists only between AE and PPro (as an NLE). You can of course also Dynamically Link stuff between AE and Adobe Audition.
4) There is also the case for using MoGRTs and Live Text between AE and PPro — these two features allow you to apply AE's Type Animation presets and even more complex AE compositions into PPro and then make changes to these AE compositions, directly in PPro. It should be obvious that not everything within AE can be edited in PPro but the level of control is way beyond what any other AE-NLE combo will be able to provide.
HTH