Who's Buried in Grant's Tomb? Ask the Average Joe to name two pre-20th Century presidents and my money says you'll get Honest Abe and the Arborist. While I share your caution as regards 'hero worship,' we live in an age where even getting your head on the the currency is no proof against obscurity. Just ask Alexander Hamilton.
   I suggest the following non-denominational holidays:

Postal Rate Increase Day
    Probably our best shot at limiting these to one a year. [Related alarmism here.]
National Dairy Products Council Day
    They gave us the Food Pyramid...and so much more. [Related alarmism here.]
Change Your Gym Clothes Day
    Here again, the goal is an annual event.
Belabor Day
Interstate Highway Funds Disbursement Day (Observed)
    Hail the Almighty Carrot. [Anything to keep South Dakota in line.]
Declassified Military Data Network Memorial Day
    Recalling a happier, simpler time.
Well-Regulated Militias Day
    Being necessary to the security of a free state, n'all, why not have a day for these brave souls to leave the safety of their fortified compounds, step forward, and be recognized?
Misgiving

   Of course, we know who gave us President's Day, don't we? (Tue 15 October 2002, 06.48 PDT)     @ #