iguana mama is like any other tour company in playa dorada or north cost. they do their trips every day and i have never seen an early booking thing.
if you come in season (that is up till march) go and see whales. pack up lots of dramamine and prepare for a wet adventure. VERY expensive but beautiful. go to damajagua waterfalls but be prepared for adrenaline rush and KEEP SAFE. if you are lazy and prefer little swimming plus lots of ron go to cayo paraiso - tiny sandy patch with good snorkeling (little crowded thou). for general knowledge you can take safari, they'd drive you through plantations so if you travel with kids they can see coffee plants, cacao, pineapple and all the stuff you normally have packed in plastic in western shops - very educative.
ask around, some of those trips can de done individually if you have a car and a willing and knowledgeable friend.
even if they tell you at iguana to book early - don't worry, i have never seen a tourist being said "no"....
