My wife liked a gift of flowers, but I sent them on anniversaries, not birthdays, and I usually got her another gift as well, and dinner out. That's probably not the answer you wanted, but (other than funerals) I've never used flowers as a gift. I'm not opposed to it, as long as you're confident the person would like them. If she lives a very comfortable lifestyle and seems to have everything she needs, flowers may please her. If she's extremely practical, they may not.
I never give gift cards. It's shocking when I read stories of how many of those are never redeemed. Also, I see gift cards that say, "Valid at participating locations," and I have no way of knowing if the location they go to is "participating." I'll probably be criticized for this, but I don't care - whether t's right or wrong - if buying power is my object as a gift, I give cash in a money envelope and a greeting card. I've yet to see anyone open it and look disappointed, and I guarantee you it won't go "unredeemed."