Angra Dos Reis/Paraty/Ilha Grande. Although not sure why you would go all the way to Rio and not visit Christ the Redeemer.

Plenty of nice restaurants. If you really want to stay somewhere nice you could stay Fasano Rio de Janeiro or Fasano Angra Dos Reis if you are willing to spend a lot of money.

Rio is a city of millions; so not exactly a great place for ecotourism. It is, however, a city built into a rainforest so there are cool hikes in the Tijuca forest. Like Pedra Bonita. Petropolis has some nice hikes and a cooler climate. Architecture there is German which gives it a different vibe and the Palace there was the summer home of Dom Pedro II the second and final emperor of Brazil