I thought both challenges left lots of room for creativity while still sticking to a theme. For example, a flowerpot inspired by spring was pretty specific and yet everyone's was vastly different! I think setting two guidelines gives a nice limit of range to the competition.
Lots of the ideas I would have said have already been shared here but I think these are different:
1. Emotion: Happy, sad. Hungry. Home. Love.
2. Shape. (Oldlady's comment inspired this idea) You could say something like "a triangular functional pot". No other rules. It could be wheel thrown and altered, slab built, pinched. does this make sense? It could be shallow and plate like or a closed 4-D pyramid. Lots of wiggle room.
3. It could also be a specific process, like a slab built plate or platter. Or a wheel thrown item with sgraffito decoration of some kind. Would that deter people, if they don't like that process? For me, a flower pot is not in my comfort zone so throwing one with an attached saucer was a good stretch of my ability.