General work bike specific tools that will let you do routine maintenance and overhauls:

Crank arm and bottom bracket tools.
If you have cup-and-cone hubs you will need cone wrenches.
A 15 mm pedal wrench is useful if the wrench flats on your pedals are too narrow for a standard open-end.
A chain tool
A cassette lockring tool and a chain whip.
Cable cutters
Spoke wrench
Tire levers
Misc. parts (grease, oil, cables, housing, bearing balls, brake pads, etc as needed).

See your bike dealer for the sizes and types of tools that fit your specific bikes. For example there are numerous bottom bracket and crank removal tools dependin on the type and make.