[New Player - Got Char boost to Lvl 60 - Now what?]

Me to be honest i would use it and make a class that you really want now. But keep in mind for it to count to legacy you have to make the same class over again and run the full storyline up to chapter 3. For the Legacy to be unlocked on that class. I did it when i first join SWTOR as Jedi Knight thinking it would unlock but come to find out after a few patches in i had to rerun a jedi knight to get the full legacy unlock. But it just depends on you and how much time you are going to spend playing.