I returned from two weeks in the Galapagos in Mid-October 2013. Darwin and Wolf were running 74 to 76 F, but we had a number of dives at other locations where temperature was as low as 56F. I did use a 7mm, and on the cold dives a 5/7mm hooded vest over the top of the 7mm. On the other hand I used the work gloves with kevler dots like these:
This was my second trip to the Galapagos, and both times I brought kevlar wetsuit gloves and the work gloves, on both trips I used the wetsuit gloves once and the work gloves the rest of the time. At least for me they were more then adequate for holding onto the rocks and barnacles. They are cheap enough and light enough that I brought a spare pair, by the end of the second week I switched to the second pair as I had started to shred the first pair, at $10 a pair I can't complain. These provide almost no warmth but it is simple to operate your camera with them on.
At the risk of starting a debate on the merits of various fins, I will add that I made a last minute packing decision that for me really paid off photographically. I switched out my normal diving fins for my Cressi 2000 HF's. I did not bring a high end free diving fin as they are more fragile then the Cressis' and as others have said the Galapagos environment is really rough. I won't speak for anyone else but for me I find I can kick with much more force with the Cressis' as long as I am in shape then with any traditional Scuba fins. I used a pair that is large enough for me to wear a thin neoprene sock both for warmth and protection from blisters on a two week trip. The extra power from the fins allowed me to get a couple of key shots at Darwin and Wolf especially appreciated when pushing my large DSLR housing. I only offer this as a suggestion if you are comfortable with larger fins, the demands of diving in the Galapagos are enough that I wouldn't take a new pair of fins if you haven't used them before or at least tried them extensively in a pool. You are traveling far enough that it is better to have equipment you know works for you then take a chance. I'm not sure when "Whale Shark" season starts at Darwin and Wolf, but these fins especially shine with Ms. Big. Both my fin choice and glove choices worked O.K. even on the very cold dives with a 7mm suit.