For situations when your couch is back against the wall, the use of dipole are typically preferred. Since they have a null listening area, they tend to be less localized and more diffused. Monopoles will likely be too directional when placement can't be optimized. You can easily place dipoles on the rear wall, but using monopoles firing forward are the rear wall likely make the sound appear it's coming from the FRONT, which is what you don't want.
Not sure how high your ceilings are but sometimes having dipoles on/in the ceiling can help with placement, even if they are not installed "inceiling". If you have to use monopoles, having them fire to the rear wall, up from the floor to the ceiling or behind the couch firing up can be effective. Surround placement can be difficult, but it's something you'll have to experiment with.