In terms of aesthetics, not necessarily conservation, another option when displaying art is to ditch the frame. (Even the always polished editors at Southern Accents have discussed this approach on occasion.) It is usually a less formal look, and of course in the case of contemporary abstract art, "going frameless" is often considered the sleekest thing. Clearly it's more economical.
But sometimes a classic gilt frame can be a stunning counterpoint to modern art.
As Emily says, "Frames are works of art in themselves. If you need to add a frame to a painting, you can really add a touch of your own personality and taste to the piece."
As long as the frame doesn't detract from the art, have fun experimenting. Ask a framer to show you a variety of moldings and see which widths and finishes are most pleasing with your painting. (Gilded moldings have different undertones, some skew toward red, some are clearer and brighter.)
Coleen Rider has a great print of Matisse's Design for cover of Exhibition: "H. Matisse," 1951, (gouache on paper, cut-and-pasted) in a slightly unexpected gilt frame. I think the gold is a refreshing choice here, as opposed to black.
For me, a mix of unframed art with very decorative gilt frames on other pieces -- whether a mirror or painting, grouped on the same wall or simply juxtaposed in one room -- is always nice. I posted this image from Elliott Puckette's house just the other day, but it perfectly illustrates the concept.
The painting in the first two images is from Annie Butrus' Peachtree Trail series.
Puckette's house was photographed by Anita Calero, as seen in Elle Decor, October 2000.