I have 2 different pearl sets that are similar to the one you posted. One has gold chain in between (like the example you posted) and the other has "illusion" thread (sort of like clear string). I don't think either looks "costumey" as I wear them both for fancy occasions. Of course I wear them for every day too when the mood strikes me.
I also have the traditional pearl set. I love it, but it doesn't get as much wear as the other two. That might be a consideration. If the set is too fancy, it might sit in the jewelry box. Less fancy gets worn more.
You could add a filler. Gold beads, silver beads, crystals, but I'd go for the clean pearl look.
Whatever you decide you can't go wrong. Pearls are beautiful, timeless and classic.