Croc papers, flocked papers, handmade papers, kraft papers, glitter papers, so many options! The hardest part really is making the selection. I store rolls (over 30!) on the pegboard with more (shhhhh) inside the hidden storage of my chaise longue, single sheets draped over the dowel, and smaller flat sheets in a storage tower in the closet. I'm always on the lookout for new papers for linings, which leads to storage situations, and marathon lining sessions. Each liner is traced with our templates, cut, inserted, and pasted by hand, and like our printing, one at a time.
I think the linings add that little something extra, and it's always nice to receive cards & letters where the extra care was put into the envelope. What about you? Think it's worth the time and/or expense?