Need Advice on Wireless router

[rodwf]

I'm wanting to install wireless router to in an office so 3 houses can share the same internet connection, i have 3 houses set in a triangular fashion to each other with a single building office in the middle, each house is about 90 feet away from the office, these houses and the office are privately owned on private land away from any other buildings.
The router would be in the offce and a computer in each house.
I'm asking for advice on what a good router would be, if i need any form of booster so each house would pickup the signal.