I think
Belle is lovely; can't imagine it being taken as "trashy".
Emmeline Belle is very nice.
Phoebe Belle has the "b" sound too close, for my ear. I like
Tallulah Belle and
Belle Cordelia. Some other ideas...
Anwen BelleEvelyn BelleGeorgina BelleJessamine BelleGwendolen BelleRosaline BelleJosephine BelleFiona BelleSylvia Belle - couldn't help it :)