Betty - not keen, think old ladies, Betsy is better
Dakota - isn't that one of the states, would be like calling your child Northampton
Dolly - cute as a nickname, but Dorothy(and it's derivatives areawaful - think old ladies)
Dulcie - lovely, claissic and elegant
Idalia - is lovely, but people will mispronounce the Id as rather than Eye - have you thought about Ianthe or Iolanthe
Isolde - Fab, like it spelt Yseult - again prone to mispronunciation
Eden - a naff perfume from the 80's or tourist attraction
Ella - Ok, bit bland
Layla - Ok, but bland
Lola - Charlie's little sister! Like it, but many won't because of the "Showgirl" connatation. Lola could be a nn for Iolanthe
Marnie - fab name, unusual without being off the wall.
Poppy - Ok, bit bland
Rosa - Ok, bit bland
Valentina - am undecided about this name. Always have been, don't like the potential shortenings of Val or Tina
Verity - Marvellous, but I like "Puritan" names, Patience, Constance, Grace