I definitely recommend the longest trip. Meals, snorkeling gear, glass bottom boat, and guides are included. Save money by avoiding peak season. The cost of a flight from the United States to Quito or Guayaquil, Ecuador, varies hour to hour, but service has been increasing. July to December is cool, reaching highs in the low 80s in September.
Seas are gentle.
There is little rain but the sky is often slightly overcast. Overall, the best time to visit may be in October or November. During my December visit, the high was in the low 70s, the sky varying between sunny and overcast. January to June is the warm season, with occasional rain showers. April through March is warmest, when highs may reach the high 80s.