Jupiter, Saturn, and the Moon will never let you down. For about 3 months every couple of years Mars is close enough to see (and this July through September will be the best in your lifetime), but the rest of the time Mars is small and disappointing.
As for deep-space objects, they take practice, and most of them require dark skies. You won't see colors in nebulae, and the shapes will be much fuzzier than in pictures. Still, with practice you can (with a large enough scope) see a faint spiral structure to some galaxies. With an 8-inch or larger scope, globular clusters change from a fuzzy blob to countless individual stars, like a bunch of salt grains on a black mat.
The Orion nebula will make your friends gasp as they look through your scope.

As for the cost of astrophotography--either cheap or very expensive. With a digital camera and some free software (astrostax), you can make good pictures of Jupiter. With a 35mm camera piggybacked on a polar-mounted scope, the camera (not the scope) can make exposures of an entire constellation that are worth putting on your wall. However, if you want long-exposure photography of distant galaxies, expect to spend more on accessories than you did on the scope itself.