What is most important for prints/giclées is that you need to have space (minimum 1.5 mm) between the artwork and the glass. That is one of the reasons to use a mat/matte/mount between the art and the glass. In Norway we use the French word passepartout for mat, which may also be associated with the tape used to stick the art to its frame. It is important that both the mat/passepartout, the tape, the filler board and the cardboard back (minimum 2.5 mm) is acid-free and ligning-free. This is to prevent discoloring. This effect was actually unknown until 1990, and a lot of art has been damaged due to the interaction between acidic materials and sun light. Finally it is good to tape the completed framing to prevent the artwork from moisture and dust.
Why does it have to be space between the art and the glass? There are several reasons. One is that if condensation occurs inside the glass, it can be transferred to the art giving water damage, mold (black, blue, red, green) or mildew (white fungus). If wet, the art could also stick to the glass. Apart from the problems with moister, some artworks made of pastels or chalk could easily smudge, so there should be a space just to prevent smudging.
Besides ensuring space between the artwork and the glass, the mat is also a framing of the art that enhances its visual appeal. For the size of the mat, the smaller the work the larger the mat. White or cream is more timeless. A non-reflective artglass reveals true colours and texture of the art. A regular glass reflects the light, and you get a mirror effect. If you use affordable frames for instance from Ikea, they are normally ok with regard to being acid-free. Some of the frames uses glass and some uses plastic. The plastic may give optical distortions, depending on the surrounding light sources. For optimum conservation, you will go for museum-quality mats and glass.
The simpler the frame, the more easily it will fit in with different decor styles. That said, a frame can mean as much to the interior as the piece itself, and there are pieces of art that can tolerate both a white, black, metal and wooden frame. The framing should complete the art, not the room.
My available limited edition signed prints/giclées are displayed in my online Print Shop.