In a perfect world, OP should stay in Zona Sul (Ipanema or Leblon). However, sitting in a taxi for 3h each day might not be the best use of time in Rio.
If beachfront is high on the list, stay at the Hyatt in Barra (if on a tighter budget, the Novotel is also fine). Hyatt is walking distance to a few local bars and restaurants.
No, the OP won't be experiencing the most unique facets of Rio, but this isn't a vacation so there needs to be some compromise.
OP: let us know what you end up doing, and if you're up for some drinks in Zona Sul on one of the days, PM me.