Mare Humorum has nothing to do with comedy. It is the Sea of Moisture which is worth seeking out to spot the dramatic crater Gassendi perched on its northern edge.
Look to the east of Mare Nubium, the Sea of Clouds, for a fine chain of craters stretching vertically and best seen soon after First Quarter. They are Ptolemaeus, Alphonsus, Arzachel, Purbach, Regiomontanus and Walter.

Further south in this crater-rich region you will find the magnificent Clavius, itself peppered with several other impact sites. The whole area will give telescope users hours of viewing pleasure.

Update! For an alternative, inverted view, here is a chart with south at the top.

You can download a check sheet for the entire list of 50 features here! (PDF file).