First, the commons :

On all my groups, first line (G1 to G7) is for tanking, line two (G8 to G14) is for DPS, third line (G15 to G19) is for healing, and the last line is for occasional stuff (like poison cleaning totem, or target a boss spawn, or things like that).
G1 is alway shot want or /attack, depending on the class.

This standardization allows me to easily move a character in another group when needed.

The way I do my pala + 4 x shaman :

G7 is freezbee pull on the pala, nothing on the shamans.
G6 is my tanking macro, nothing on the shamans. I use this to build up aggro when necessary.
G5 is "taunt" on the pala and LB on the shamans
G4-G2 are various less useful pala stuff

G14 is LB on the shamans, and tanking macro on the pala
G13 is FS+LB on the shamans, and tanking macro on the pala
G12 is Chain Lightning on the shamans, and .... yes, tanking macro on the pala
G11 is a castrandom of shocks on the shamans and tanking macro on the pala
etc ...

G19-G15 are dedicated heals (I have a healer shaman). Each of these keys are set to tanking macro for the pala, and LB for the DSP shamans.

This way, I have a lot of spare keys, never have to worry about tanking, and don't fear to lose DPS when healing.