The funny thing is that I personally have ended up creating a "large" google sheet with all the Messier objects which my rig could image, and added a column for "when" to image (i.e., spring, etc). It's served me quite well.
As I said in another comment, a true killer feature would be to image my yard, with all the obstacles blocking the sky, and intersecting the available sky space with the trajectories of those objects, and use that info to actually tell me what I can image.
As I said in another comment, a true killer feature would be to image my yard, with all the obstacles blocking the sky, and intersecting the available sky space with the trajectories of those objects, and use that info to actually tell me what I can image.