I would say, go the apartment route.
I've been going to Brasil for 10 years now and only spent two nights in a Rio hotel (that I'd
) and one of those was at the JW Marriott courtesy of AA when I got a VDB.
1) Cost : US$80-140 should get you a decent to very nice apartment that's as good as a room at the Marriott at 2-3 times the price. IMO the hotels in Rio offer poor value for the $$$ charged.
2) If you get lucky with a member of the fairer sex you may not be able to bring her back to your room. The Marriott's fine but some hotels assume that if a gringo is with a Brazilian woman she must be a prostitute
and security may stop you as they want to maintain their family reputation. You entering the elevator with a Brazilian woman could prove unduly shocking to families who've just walked past the transexual streetwalkers on Avenida Atlantica.
I'm lucky enough to rent from a friend of mine who gives a good rate and doesn't need a deposit. However it could be a bit daunting if it's your first time. What I would suggest is book a hotel for 2-3 nights to get a feel for the city and decide where you want to stay. When you arrive go to one of the apartment brokers with English speaking staff. They will tell what's available with photos and prices and often show you the apartment so you're not committing in advance to anything that you're not comfortable with. Most apts. have a 5-7 day min. stay so even with 11-12 days of your vacation to go you'd be fine.