Strictly case by case.  I absolutely hate multiplication of races in fantasy worlds, so you'll have to make a very good case if you want to play a wierd low LA race.  (unless you want to be some kind lost race from Xen'drik or a mutant from the Mournland)  I'm also pretty okay with template races who have a conspiracy, like the Necropolitans or that one immortal race from the psionics handbook.<br/><br/>Racial substitution levels and paragon paths are another issue, which I'm somewhat more friendly towards.  (since I'm a bit nostalgic to the days when Elf was a class of its own.)