You do not need any ground rods since yours is an attached garage. You can use a main lug or a main breaker panel. You do not need a common disconnect.
The easiest way to go is a main breaker panel as it already has 2 bars that can be separated to give a neutral and a ground bar. I went with a 100 amp, 20 space GE panel from Home depot that included a 100 amp main and 5 single pole 20 amp breakers (called a contractors package) for $50 bucks. hard to beat and Lowes has the same package. A 100 amp main (disconnect) is fine even though you are feeding it with 60 amp feeders.
Here is also a Square D Home-line 100 amp main breaker package for $50