Great set of names here - lots I like (plus a few I really don't!)
My two pennyworth:
Seraphina - very pretty, but way two frilly for me - I imagine someone who's a bit 'precious' and high maintenance. Also asking for trouble if she can't quite up to her name's angelic image...
Vesper - Bond girl, monks' evening prayers or prize racehorse. Lovely sound, though!
Salomeh - prefer Salome spelling, but dodgy Biblical associations would rule it out for me. I'd imagine an exotic femme fatale.
Imogen - nice but overused at the mo - I know loads of little Imogens.
Astrid - love this (and Scandi names in general). It's strong and intelligent sounding - a bit clunky, but in a good way
I know a lovely four-year-old Astrid who goes by 'Asti'.
Evelyn - fine, but a little on the dull/dated side. Evie is overdone now.
Beatrix - Bluestocking. I picture an older lady who's something of a battle-axe!
Estella - really like this, and think it's underused (possibly because of the not very likeable character in Great Expectations).
Xanthe - love it - my favourite on your list. The X makes it intriguing, without being too 'out there'. Slightly artistic, quirky, hippyish vibe.
Pandora - Adrian Mole's treacle-haired girlfriend. It sounds 'heavy' to me. And the Pandora's Box myth isn't the best one to be associated with imo. Pan makes a cute nickname though!
Genevieve - really like it; it's grown on me lately. Lots of good potential nicknames (Ginny, Vivi etc) and a sophisticated (but not weird) sound.
Personally I'd narrow it down to Astrid, Estella, Xanthe and Genevieve, with Xanthe being my top choice.