Coming up with a host of examples is a bit more than I care to undertake at this time. I'll do a sliding scale based off the incident in question:
Do Nothing - Current Situation. It's a one-off incident, specifically one that happened PRIOR to Franken's election to off, and it's an incident that's up to interpretation as to its severity. Al Franken apologized sincerely within hours of the accusation and his accuser accepted the apology.
Censure - Similar to the current situation, but with denial and deflection, rather than an apology. Again, it's a one-off situation, but in this instance, the conduct of the accused is more unbecoming of a U.S. senator. Equally, if the incident happened DURING his tenure as a U.S. senator, then he should be censured, even if he displays genuine remorse and the apology is accepted.
Resignation - Regardless of apologies, if three-five incidents are reported and corroborated (and you can quote me on this if it comes to fruition later), then calls for resignation are completely fair game. I don't care about the circumstances, three incidents show a pattern of behavior that cannot be overlooked. OR, if there was a single incident that involved some form of rape, then one incident is enough to call for resignation.
Expulsion - Six or more incidents are reported and corroborated, constant denials and refusal to resign. Multiple instances of rape.