The above pics are all Ilha Grande, beautiful beaches, average little township, good little beach bars/restaurants, a little pricey.  If you are deciding between Parati/Trinadaje and Ilha Grande (or something else), drop Ilha Grande...its beautiful but not a lot to do and we loved Parati etc better.  It could be a mission to get to as well??

All the above are Parati.  I do think you'll love it.  Splurge and hire a boat for a day, alone or hook up with fellow travellers.  Really beautiful.

Trinadaje:  very basic but dozens of beach bars and THE most beautiful beaches.  Lazy week could be spent here.  Lots of walking to waterfalls/swimming holes but plenty of beaches close by.  The most spectacular beach is a 10 minute walk.  The local beach is also stunning.