Ive been leveling every class as they're available, through the MSQ/Dungeons.
Im on Dynamis, so the double DP helps significantly. I frontloaded EXP via the hunting logs so that helped.
Currently have all DPS classes at 58, and Im running them each through Snowcloak. I had hoped that Snowcloak would take them to 59, and then Keeper of the Lake to 60 before ever stepping foot in Ishgard but... ahh well.
Its fun and I enjoy getting to play each class through the dungeons, im wondering if itd have been better to just do one class.
The reasoning for doing it this way was based off of the notion that at the end of (insert the current expac here) when the MSQ is "To Be Continued", people just go back and level their classes anyway... So why not just take them all through more organically?
Still... I dunno.
Feedback always welcome.