Lots of great Italian options to try Nick.
Feudi di San Gregorio wines are widely available, the Cutizzi Greco di Tufo is exceptional, but you can't really go wrong with any of their wines from the triumvirate of Southern Italian whites: Greco, Fiano and Falanghina.
Lots of great stuff coming out of Sicily now, try some good quality Grillo or Lucido Catarratto from the west of the island (Centopassi, Marco de Bartoli, Caruso & Minini, Tasca d'Almerita/Tenuta Regaleali) ... but you specifically mentioned recommendations for Etna Bianco, so here's a few :
Al-Cantara- Occhi di Chiumi and especially Luci Luci
Palmento Costanzo - Etna Bianco di Sei
Pietradolce - Etna Bianco Archineri
And at the top end:
Benanti - Pietramarina (preferably with some bottle age) but if price is too steep, try one of their single Contrada whites for half the price.
From the Veneto, try some Lugana or Custoza. Monte del Fra are a top producer for both. Soave from Pieropan, Ca' Rugate or Coffele (TWS)
Vernaccia di San Gimignano from Tuscany: Panizzi or Montenidoli.
Verdicchio from the Marche : Villa Bucci (TWS) or Umani Ronchi
Others have mentioned the Friuli region, but don't miss the far north of Alto Adige (South Tyrol) too. Cantina Adrano and Terlano wines are excellent, from Pinot Bianco and Pinot Grigio.