Those are so cute!

We often do "kiddie art" cards (handprints or finger paint on huge sheets of paper, then I cut out "good parts" to turn into cards since it's less stressful for me to have them make a big mess instead of trying to get a "good" handprint, footprint, or picture on each individual precut card). In terms of tacky vs cute... well, we only send those cards to family (who appreciate the extra love the girls are putting in) or close friends who know the girls or who would also appreciate that sort of love. Co-workers, the postal clerk, etc get home made but less "messy" cards.
One thing we have done in the past is to make paper ornament cards using the girls' hand or foot print as the mold. Basically trace their hand of foot to make a template. Then I built up a "lip" of salt dough around the tracing and let it dry (so you end up with something that looks almost like a cookie cutter in the shape of their hand or foot). DD1 enjoyed ripping up scrap paper and we mushed it all together into paper pulp, then filled the "mold" made from their handprints while dd2 added petals and other "stuff". The end result was a thick piece of paper in the shape of their hand or foot... it sounds like a lot of work but it really wasn't. The girls had fun and the ornaments weren't fragile or anything like that.