I highly recommend running Glenwood Canyon from Grizzley Creek to either Two Rivers Park in GS or South Canyon. There's something there you don't get on the Upper C - its called "continuous current." There are also a lot more of the fun little Class II rapids. The only advantage Pumphouse has is that if it gets windy on the Upper C, one day next season you'll appreciate how it helped build character as an oarsman, you'll get a graphic example of a raft's aerodynamic properties, and also it will underscore how similar an on-river experience can be to rowing across a lake into a strong headwind.
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse