Aside from being a very sexy article of clothing on a woman, stocking legs and feet are extremely fun to tickle whether they are in pantyhose, thigh hi's, gartered nylons or even knee hi's.
I've always been partial to tickling my lee's feet in smooth, sheer, silky hosiery.
Nylons definitely allow a tickler's fingertips/nails to glide more effortlessly over a ticklish foot and the sensations a ticklee receives are extremely different, a bit more heightened (so I've been told) than those she feels on her bare feet.
If your ticklee's feet are prone to swift desensitization nylons greatly assist. Even if your style of tickling is fast and hard they act as a sort of buffer and also intensify the feeling of tickishness.
If your ticklee has extremely sensitive feet a slow torture some teasing, itchy kind of tickle in nylons will have her climbing the walls in a matter of minutes. I love using my nails for this but a simple plastic picnic fork that I lightly trace over every inch of my ticklee's feet, including the tops & toes, induces hysterical laughter, wild shivers and multitudes of goosebumps every time!
I have tickled women who claim to have had minimally ticklish feet but once I tickled them in nylons the level of their ticklishness jumped substantially.
And let's not forget how much fun it is to nibble on a set of wriggling toes, or an instep or heel through silky sheer stockings then when your lee least expects it you bite throught them, peel them back and work on that now ultra sensitized bare foot for all it's worth!