Right now all posts are treated equal, with the newest post being displayed with a big full-width size feature image on the front page. The older posts are pushed down and are displayed in small thumbnail sizes (259px wide). I wants to make a custom function that enables popular posts (say more than 20 comments) to be displayed in a bigger size (say taking the space of two thumbnail columns, around 561px wide). I understand I may have to write a custom function to do this, but I want to ask for the most efficient method to do this (i.e what files should I modify, etc).
Thanks.