I'd say go with the 802.11n. It's best to futureproof yourself. If you end up with a setup where you are transferring files to a DVR or other media box you'll want the speed. Same goes for something like a PS3.
My network at home is a bit insane. Cable modem goes into Airport Extreme 802.11n router, this has the main wireless network for the house. This router feeds another dual band 802.11n D-link router which provides one wireless network for the video game systems, and another for the Tivo's in the house. When the Tivo's are transferring data it will really bog down whatever wireless network is in use, so I find it best to give them their own. Then there's a 8 port gigabit switch which is linked to the main Airport Extreme for internet, but also provides a high speed backbone for the computers in the office/studio. Finally there is a second Airport Extreme back in the office that expands the wireless coverage and also has three hard drives connected to it as small file servers.