If she spends a lot of time working, then maybe look for something which will make her working environment nicer, or her work easier.
Like if she has to spend a lot of time driving to and from the apartments she manages, then maybe get her some nice audiobooks to listen to while she drives, and/or a gift certificate to a place which will clean out her car, or a fun (scented?) decoration for her car. Maybe a new set of nice driving gloves.
Or if she spends a lot of time in an office, then something cheerful for her office (a really cute pot with a nice potted plant? I've seen these darling little dryad pots lately, hang on...
link here like that)
or one of those decorations for computers (things that perch on the corner of a screen, cheerful and fun stickers that apply to the sides of the computer, etc.)
I don't know much about tv, but I bet they have decorations for televisions too. Probably you could even use the same ones as they sell for computers.
Or maybe go the other direction, and give her something that will give her a break from what she spends most of her time doing.
Like a gift certificate for a massage or a pedicure or something like that?