I like Felicity with Rosalind and Gayle tied at second place.
My thoughts:
Felicity: Feminine yet accomplished. Kendall comes to mind and that is not a bad thing. I also like the male version of Felix.
Rosalind: Not an unusual name and yet underused. It seems gentle and stylish, not shouting nor bragging about anything. Good natured and cultured. Shakespeare would have approved.
Gayle: Happy and joyful and a red coloured name. I like the rounded nature of the G in this name and prefer it in appearance to Gail as a diminutive of Abigail. I don't find it 80s in any way, none more so than Abigail, as it has been used as a nn for many years as Kate has been for Katherine. The spelling with a y is nearer to how it was once written IIRC. As well as meaning joy, I think it's also related to gala meaning rejoicing and to the word singer, as in nightingale and Keats's ode to the bird's song. Robert Le Carre used a Gail or Gayle (can't remember which version) in his recent book as a barrister and Gail Trimble, the classist now at Oxford also comes to mind as does Gayle Hunnicutt, a very striking actress in her time and involved with the National Trust.
Clementine: I like this although I'm not sure whether it will be rather faddy as it's only been used more recently. Clementine Churchill and Kate Winslet's character have helped boost its popularity. It vividly brings to mind the colour orange which is fine but what if she doesn't want to be associated with that colour for all her life? Just a thought.
Jacqueline: The nn Jackie would deter me and all I see are captions to photos of people with mullets in a magazine, I'm afraid. The Kennedy connection isn't entirely desirable either. I think if you were French if would be easier to get away with, perhaps. Apart from this name, I very much like the names you have shortlisted.
Like Cressida too. Regarding Mary as a middle name, have you considered Marigay if you like the name Mary and Gayle? I know of one who is great, may be a bit too SW3 sloane but it might be a way of adding in another name.
Eleanor - timeless, elegant, acceptable anywhere, it has the romance of the Acquitaine connection. The only downside is that I don't like Ellie much. If your surname is very plain, I think this might be a bit dowdy as the Rigby element might come into play.
Christabel - I think of a suffragete, so there is strength in the connotation and feminity in the sound of the name. There's also a Balenciaga scent that has a similar name.
How many syllables does your surname have?