For as big as small town Brandon is, there doesn't seem to be very many of us on here ... that's for sure.
If you're going to MK, for example, Guest relations is right to the right when you walk in. Obviously it would depend on what time/day you go, but we just activated my mom's past last week there. There wasn't a line and it took her less than 10 minutes, and she needed a birthday button.
If you forget to mention that you need your parking refunded, they won't ask. I completely forgot to mention it with mine. We exchanged my boyfriend's pass at Epcot, and were waiting in a longish line, when a CM had us go to a regular ticket window to do it. I've also done it during a previous year at DHS ... I don't necessarily think a separate trip to DTD is needed, personally, since you're already going to Guest Relations any ways ... plus, who wants to add more time to the trip, because I can never find parking at DTD.