Trish...It's about 50 km from Puerto Ayora to the Baltra airport as you will see upon arrival. Best to leave Puerto Ayora, morning of departure, by 11:15 AM. You can either take a taxi to Itabaca Canal and do it yourself from there ($18) or have the driver accompany you all the way to the airport for assistance ($35).
A) Take a taxi to Itabaca Canal ($18 and 40 minutes) and then load your luggage on top of the ferry. Sometimes you do have to wait for a ferry. The ferry is $1 pp.
On the other side of the Canal, you retrieve your luggage from atop the ferry and put it on an airline bus, which you might also have to wait on. From there, it's 10 minutes or less to the airport. Find the Aggressor guides at Arrivals in Aggressor shirts outside baggage claim. Most of your fellow divers will arrive on Avianca at 12:50 PM. Seeing a group of passengers with dive gear is always a dead giveaway.
I second La Garrapata (tuna always great, especially with pepper sauce) and will add Isla Grille! SolyMar and Red Mangrove more upscale than La Fiesta. Waterfront hotels are limited. Angermeyer is nice, but you have to get a water taxi anytime you want to go to town....and back.