Even with Nanaly in your team, Spica is very useful as second, strong and cheap archer.
Chydis is must-have-for-everyone plat healer, so I'm strongly recommend to save up DC for few copies of her.
Golden pirate (Myre or something like that) post AW have a gold-digging ability (like Betty and Lyla) + her skill-AW for a 20+ seconds makes every shot a giant AoE BOOM!, which is very helpful (and profitable) against swarms of weak enemies.