Eric Ross writes:

Any suggestions for making this flight as positive as possible for her?

Fly her to dinner someplace nice on a beautiful day. Done correctly, this
can become a very expensive habit.

Take along your flight instructor for the first trip as a "thank you" and
as a way to ease your wife's concerns (and to make the trip easier for you.)

Or...you could go up on a bouncy summer day and do stalls with her. I know
someone who did that and cut his flying expenses to $0/year.

--kyler