Seeking advice on alt character set up

Hi all, I just now finished leveling my first 60 mage to level cap and while I gear him up and collect gold, I want some advice on how to plan out alts.

Given the nerf to mob tagging with lower levels and killing with a max level, which of these strategies do more experienced multiboxers feel is most ideal? I am undecided on the class I want so I may want both.

1) solo grind on rogue &/or shaman to 60 on same account
2) use my second account for rogue/shaman and assist with 60 mage by running through dungeons.
3) use primary account for one character and secondary account for the other and duo grind.
4) other

Any thoughts are appreciated as I am not super experienced but I know the game well.

thanks

Dungeon boost.