Miaka and Yui from Fushigi Yuugi are a good pair. You could do their priestess or schoolgirl costumes. Not super simple, but not too complex. Or Faris and Lenna from FFV (in-game sprite outfits). Also Heather/Maria/Eileen from the various Silent Hill games would be pretty simple to construct.
EEEK! Oh my god!! He... he's ALIVE?! What the f-?!? YUCK!!
Upcoming costumes: Syrenne (TLS), Rydia (FFIV-LoV version)