A few plant lights, and few more plants and you'll hardly realize you're indoors. Outdoor furniture works beautifully in many interiors and is usually more economical than its interior counterpart. Cast or wrought iron tables are solid enough that you don't have to worry about knocking into them and scattering everything on top. They also make unusual wall ornaments or screens. Put a vining plant in a pot at the base and let it twine its way through the ironwork.
Fountains are a wonderful way to bring the outdoors in.
Although I do know a man who has a 6' high fountain and equally large basin taking up a lot of their living room, most of us will be well contented with something more modest. If your fountain basin is large enough and you have good lighting, you could even try growing a small tropical water lily in it. If you're artistic, try your hand at painting a mural on the wall to make it seem like you're looking at the garden. If you lack that talent, you can get amazing results with an overhead projector. Or simply cluster container plants and add a gazing ball or statue to simulate a garden.