Everyone in Pittsburgh should visit the Conservatory it is a very beautiful place and you can learn alot about plants so its fun and educational making it a great place for family/kids.
I recommend trying to go more than once too as they change up the themes/plants with the seasons. I remember going in the summer and then being really surprised at how different the place was in winter.
During the winter time they have a Christmas theme and a light show at night making it a great date spot.
but dress properly it is a botanical garden so it can be humid/warm