Travelling from Guayaquil airport

Your best bet, safety-wise, would be to fly to Manta. There, you can take a taxi, about $25-30 considering your fresh "gringo" faces. You can also, take a bus from Guayaquil (the bus terminal is not far from the airport)  to Manta, Bahia or San Vicente, but I personally consider a bus traveling out and to Guayaquil not safe, although many might say nothing happened during some particular trip, bus hold ups is like a national sport on the coast. So, basically you risk loosing all your possessions. There is not much to look at on the way, take a plane.
When you look for a taxi in Manta, do take the first or the second keeping in mind the price I mentioned. Do NOT create a commotion over there between the taxi drivers that 2 gringos are looking to go to Bahia: you may reduce your chances to 0 of ever getting there. Well, and if you happen to get jammed up, don't resist, even if you have skills you'll lack the hardware, so DO NOT, people that don't resist don't get hurt.
Good luck and enjoy.