For Galapagos, bring cash for tips - use a money belt or similar to conceal your cash. There are a few ATM's, but you'd have to search for them and you'd be losing precious touring time. One guide is from the U.S. and could possibly cash your check at home, but the other one is from Ecuador and there's no way he'd be able to cash your check. Don't bring anything over $50 bills for tips.
And bring lots of smaller bills, 1's, 5's, and 10's, for your purchases in Ecuador - most places won't give change for 20's. And by the way, since the ATM's give out 20's, they'll be useless for your smaller purchases.
FYI, the Marriott and the ship have huge safes. Hacienda Cusin had no safe.