Stationary and sending cards is one of the great refined pleasures of age--you get to express how much people mean to you in carefully beautiful handwriting, choose unique and lovely cards, and give someone you love a great surprise in the mail. There are two components of this for the writing set: the cards and the seal [or stickers/stamps].
You need both great stationary and interesting decoration:
Get unique cards at places like: The Grove Street Press online, and the very famous Ana's Papeterie
Get wax seals at: U.K.'s British ebay site: very unique! I have often pored over each antique piece. On Etsy, the two people to get them from are ReminiscencePapers [for particular, different fonts letters] and TheSupplyGuy [for tiny incredible images]. Love the zodiac signs set of wax seals and the gingerbread man.