Capitol Park is a mini-park located right in front of the capitol building and a relaxing place to be. It provides places to sit, a picnic area, a lot of trees (which is awesome if for those who may end up visiting on hot days) and brick paths for brief walks. It is also a great place to take photos of the capitol building and even portrait photos. As it is right in downtown, the park is not too far from restaurants, bars, etc. Those who enjoy parks and soft scenery will like it here, and even those who aren't will probably enjoy spending at least several minutes in this area.
The Idaho Botanical Gardens are the largest gardens in the state and occupy the grounds of what was once the Historic Idaho State Penitentiary's farm. The botanical gardens themselves are huge and filled with all kinds of hidden corners and theme gardens that make it a pretty magical place. Don't believe me? Spend a morning at the Meditation Garden enjoy the silence among the creeping ivy, ferny trees, and trickling stream. Or, take your significant other to the Heirloom Rose Garden in springtime and see the bright pink and green leaves against the historic penitentiary. It's beautiful, plain and simple.
Another nice part about the Idaho Botanical Garden is that they organize monthly events and summer concerts so you get a chance to hang out in the gardens in the evening. Every month, they invite wine producers, farmers, and chefs from around the state to come and set up so the public can sample their products. If you're visiting in summer, keep an eye out for the Outlaw Field Summer Concert Series. They invite groups to come and play in the meadow and you can bring lawn chairs and picnics and enjoy some food and music in the great outdoors. It's honestly one of the best plans I can think of for a late spring afternoon.
Admission to the gardens is $7 for adults and $5 for kids and seniors. Don't miss it!