I have sold some of SMC's SMC7904WBRA-N routers to clients. It's got N-draft capabilities, and works very well. One client has an old house (those with the very thick walls) in Boston where he runs his business from. I get signal all over the property, even in the "donker hoekie" behind the garage that is at the back of the house. The router is right by the front door, so the whole house and the garage was between me and router, and it still gave me a "good" signal.
You can look for something like that, but without the modem.