R' Hirsch published 1000s of pages of writings. If you don't have time to read them all but would like to spend some time on samples of the various types you might want to try the book Timeless Torah. This is an anthology that Jacob Breuer, Rav Joseph Breuer's son, put together in the 1950s. It contains choice excerpts in English of R' Hirsch's commentary on Chumash, Nach, and Tehillim and several essays from the Collected Writings, ie essays that originally appeared in the journal Jeshurun.
The hardcover edition is out of print, but you can buy some old copies on Amazon. However, paperback reprints (that I believe are new) are also available. I'm not sure who has been publishing these reprints - you'll find them also on the German Collected Writings and Pentateuch, but we are most happy to have them.
As a side note, I'd like to mention that this post is the blog's 300th. Now, I know that many of the posts here (mine in particular) are not nearly as substantive as those of many other blogs (On the Main Line, for example) but my goal is to collect all sorts of information about TIDE, Hirsch, and Germany Orthodoxy and to enjoy it and share it. In other words, R' Hirsch and other great German Jewish rabbanim already did all the hard work and great writing and I'm just putting it out there. I thank HaKodesh Baruch Hu for this opportunity.