I don't review as much as I have in the past. I do review for journals on which I sit on the board (only two now). I also review for journals for which I perceive a "debt" - journals that helped me when I was getting my career going, journals that have been helpful in getting difficult articles published (ie editors willing to listen).
But now, when I get an article to review that I will review, I send the following back to the AE:
I would like to involve my postdoctoral fellows, Dr. Brilliance Personified and Dr. Can't Believe How Hard She Works, in this review. We will discuss the paper, and they will offer comments. I will write the final review. They will be instructed that the paper is not for discussion outside of our meeting, and in the ethics of reviewing. By doing this, I hope to help train them to be reviewers for your journal in the future.
Potnia the Relentless
Follow up from AE:
Hi Dr. Theron,
That's fine. As long as you are overseeing the review and have the most input in the assessment, you can review the paper with your postdocs.
I appreciate your letting us know.