You have the Low Amazon Rainforest, with some very nice lodges – paradises for the nature lover – almost all of which are in the Yasuní and Cuyabeno Natural Parks, reachable after a short flight from Quito (to Coca or to Lago Agrio) and then a few hours of boating by large motor canoe.
And you also have the beautiful but pricey river cruises: along the Rio Napo, for several years now, some luxury ships have been operating offering river cruises. You sleep and eat on the ship and make excursions into the forest along the way.
And then you have the higher Amazon forest, which you can easily get to by car from the Andes. This area is less interesting for the nature lover, but is more suitable to visit as a family: the lodges have swimming pools, there are opportunities for rafting, canyoning, etc. in addition to the excursions in the forest. The area around Tena (Archidona, Mishualli) has nice hotels. If you want to go there it is best to make the following loop: Quito – Papallacta – Baeza – Tena – Puyo – Baños (or vice versa). From Baños you travel further south through the Andes.
More info on lodges and river cruises in the Amazon jungle can be found below.