what kind of riding does your fiancee like to do? because that will influence what board would be best for her.
i can tell you a few things about some of the boards though just in general
i would not buy a feelgood es. at all. it is a lot of money for a board that is moderately stiff with no pop. i had one as my 2nd board and it was great for about a month and then it completely died. i decided to give it the benefit of the doubt and demo one last year and i noticed the same thing, moderately stiff, but no pop whatsoever.
the stria, however, is a fabulous board. it is a bit softer than the feelgood, so definitely a more playful feel (it is also a twin, so it will have symmetrical shape and flex). this is definitely a great all around board i would recommend for anyone (except if you are charging huge backcountry lines or doing lots of street jibbing)..