My daughter as part of her "college experience" did a 4 week mini semester in Ecuador and the Galapagos.
Ecuador was a land adventure, but the Galapagos was on a small yacht (16 people)
She said the small boat was great!
Here is an example of the size boat she and her classmates were on: https://www.galapagosislands.com/cruises/yacht (example only)
She went in early January and the weather was perfect

let us know what you decide