If you book the current Celebrity offer of 20% off the cruise they will also give you a $750 flight credit or another $500 off of the cruise price, so it essentially pays for itself since it includes the transfers and the flight to Baltra from Quito. Go with the extra free day in Quito if you can, and the included Quito Day Tour takes you to the must see's of the Historic City Center and the Equator monument area.
I recently became a Certified Celebrity Travel Advisor after spending many years working with the independent Ecuadorian cruise lines (I love them too). I have lived in Quito for 13 years and am happy to answer any questions.
Check out my Ecuador & Galapagos FAQ page, you might find it useful.
https://ecuadorunlimited.com/ecuador-travel-tips/
Happy travels!
-Aaron
