Roles that you wish Sivaji Ganesan had taken up...

[groucho070]

I can think of another category: a movie like Naan Vaazha Vaippaen - how it would have been with Sivaji and Rajni exchanging roles?

Now you are talking, my friend. With NT, we saw nothing extraordinary. But Rajini in it, we'd be sitting up and lapping up the good performance, and when NT appears in the middle, we'd stand up and applause. We can easily see this, having had witnessed NT doing a standout guest roles in films like Kaval Deivam or even the dull Cinema Paithiyam as himself.