Top digital camera settings Nikon D5000 Suggestions Looking?

I'm shooting with a Nikon D5000 and am really not happy with the quality of my photos. I have the 18-55mm and 55-200mm lenses. Tomorrow I'm going to a garden with lots of scenic opportunities and was wondering if you could give me some advice. The day is supposed to be sunny and I would like to come home with more than washed out colors. While shooting I can see the exposure is to bright or dark but can't compensate while in the scene modes or shooting straight auto. What would you recommend in lens choice and shooting mode?

If you could post a photo an example of what you're calling "washed out", it would be helpful.
What time are you going to be at the garden? The best light for photography is early and late in the day. Midday sunlight generally gives less satisfactory results on a sunny day. Your camera's light meter should be giving you the right advice, and should not be producing "washed out" colors (which sounds like over-exposure). If you're not satisfied with what you're getting in the auto or program modes, my suggestion would be to shoot in the manual mode and adjust aperture and exposure yourself

If it was me:

Shooting mode: Full manual focus and exposure with the ISO as low as possible (ISO 100 to 200)
Lens choice: both of them

Also take a tripod and a shutter release cable (or use a monopod)

Sorry I can't help with "scene modes". None of my cameras include it and the reason I bought a DSLR was to have total control of the camera.

The problem is that you ate using your DSLR like a cheap point and shoot. Learn how to control exposure yourself in manual mode. Your photos will continue to look like they came from a cheap point and shoot as long as you keep using auto settings.