Just 2 will do:

1, An everyday road bike to put on the miles and keep the pounds off doubles as a commuter

2, Fendered roadbike, more gears for those longer rides with friends and adventures into parts unkown

Oh, yeah..............

There's the Mountian bike which doubles as the winter bike cuz it doen't mind salt and can carry, drag or pull anything and then a Tandem just in case I want to bring a freind along, oh and a folder if I ever wanted to hop the trian into the city and a 3 spd for Sunday rides, very proper you know. Oh, and I forgot, a project bike to tinker with.

See 2 bikes are all you need.