I absolutely love making valentines for this event. Gives me the perfect excuse to haul out ALL of my supplies and play with EVERY technique I can think of.
Here are are few of my mixed media cards with lots of layering. I use just about any sort of scrap from my stash of materials - fabric paper, muslin that I have hand stamped and colored with acrylic paints, collaged papers, old book pages, hand-made paper, package wrap...basically whatever I find in the studio that just looks great. Oh yeah, and stitching.
These two are samples of a very clean, simple design I like to do. It's so fun and easy to discover a terrific looking heart in just about any piece of fabric paper, cut it out and hand sew on an interesting old rusted washer or a bent wire metal shape. Glue the heart onto some nice paper backing, then glue that to the front of a card and the effect is quite elegant.