I'm glad to see that many have already provided useful answers to this question. I can second the recommendations for the Divrei Shaul and the fantastic collection on Halacha Brura. If the passage in question refers to a verse in Torah, you can see if the Torah Temimah cites the aggada and see what he has to say in the footnotes.
Not mentioned above are the two volumes of HaMafteach by Moshe Schatzkes. (This is NOT the same Moshe Schatzkes of Lomza who was RY at RIETS in the post-war era.) The first volume (of two) is available online. I am not familiar with these volumes, so I don't know how useful they will be for you.
Finally, you'll find many interpretations dispersed amongst other works not necessarily dedicated to aggadeta. To find some of them, do a search of hebrewbooks.org using a two or three word phrase from the aggada in question.