The SeesStar app does a good job in this respect. On the main page you have a list of Tonight's Best, but more importantly, in the SkyAtlas search page there are four curated lists that are quite useful, Deep Sky Galaxy, Deep Sky Nebula, the full Messier catalogue and a few objects from the IC catalogue. For each item, if you click on the down arrow next to the Current Altitude field you will get information about when the object is visible, its altitude and the approximate azimuth, which can help plan your sessions. If there is a green circle in the lower right corner of the image you should use the light pollution filter, it helps with emission nebulae at the cost of requiring longer exposures.
The big ticket items are M31, M33 and M42 in the winter, M8, M16, M17, M20 in the summer (visible right now very low in the southern sky after midnight), they are all quite big - some require stitching two shots side by side and M31 needs at least 5 - and can be acquired with 5 min exposures, but most of them are quite faint and galaxies especially will show up as a smudge, I consider 30 minutes as the standard minimum, the longer the better of course, until field rotation messes up the image too much. In the northern hemisphere M101, M51, M65/M66/NGC3628 (Leo's triplet), M81/M82 (Bode's), M84/M86 and the rest of Markarian's chain. If you are not doing post processing of the stacked FITS file and just use the JPEG, play with brightness and contrasts before ending the capture and saving the image.
After you do all these there are quasars, supernovas, hundreds of asteroids that move fast enough to capture that in one or two hours, double stars, variable stars, the T Coronae Borealis nova expected to blow up this summer and on and on. If you can live without sleeping you can fill every minute of clear night sky you can get.
