As a part-timer I obviously have different priorities than full-timers do, but I'd say raises, harassment, guaranteed hours, and breaks.
I think part-timers should be making in the neighborhood of about $15.00/hr, minimum. The sooner healthcare is available, the lower we can go on that.
In addition to the raise, I'd like to see skilled pay raises eliminated with employees that have it currently grandfathered in. The company claims that there are no skilled positions anymore anyway, and the raises are being abused as a form of favoritism. Fighting the favoritism risks throwing union brothers and sisters under the bus (I can think of one incident in which an entire class of employees lost their $1 because someone grieved it saying they should get it too), and accepting the fact that your supervisor won't give you the raise means performing the same work for less money (seniority and time with the company notwithstanding).
Increase the daily guarantee for PTers up to 4 hours. We get paid 4 hours for vacation and option time, our daily guarantee should be 4 hours too. Make the guarantee and the point at which an employee begins to earn OT the same. Full-time employees are both guaranteed 8 hours, and earn OT after 8 hours. I think it should be the same for PTers.
As
@Indecisi0n said, a real penalty for harassment. Quoting company policy and requesting action "up to and including discharge" on the grievance raises eyebrows, but doesn't actually do anything.
Finally, breaks. We don't always get ours. We have to ask, demand, whatever. And sometimes we still don't get them. I've got better things to do than sit down in the UPS building for 10 minutes after I'm finished working, just to collect the money that I'm owed. But more than that, the important issue to me is the break itself, not the money. As we all know, UPS only responds to monetary incentives. I'd like the penalty on supervisors forgetting to give us breaks, or straight up not allowing them, to be 1 hour of paid time, paid as though you had worked it (in other words, if you finish at 4:45 hours and didn't take break, you'd be paid for 15 minutes straight time, and 45 minutes overtime). A 5:45 hr day instead of 4:45. If that makes sense.