So even if you aren't planning on selling your house any time soon, go ahead and landscape. It gets more valuable each year, provided you plan it properly and maintain it. Don't landscape just because you think you'll get rich though. Do it because it improves your quality of life, your neighborhood, and your environment. Ask any realtor what is important in marketing a house and they will tell you-curb appeal.
Some houses just look better from the street than others.
They may not be a better house, but they have that certain something that makes you want to see it. You can create alot of curb appeal with a little bit of landscape work. Make sure the lawn looks neat. Keep it mowed and edged. Fertilize it and reseed if necessary to create a lush green carpet.