I'd suggest doing everything on one character; unless you want variant races/genders. All mine are female: I main a Seeker Miqo'te Smn that I plan on leveling up most of the jobs on. However, I also have a Lalafell bard that I just hit 50 with, as well as a lowlevel Roe... of which I might fantasia at the expansion to see how the new race (thats been hinted at lightly) is, if its released.
My fiancee has a 50 DRG Miqo'te main, a Roe alt (that has a 50 sch and working on crafting), and a lala.
A FC mate of mine has fantasia'ed their character several times; i am unsure if they can even buy any more. Alting for race is the best solution as Fantasia is currently limited to how many you can buy.