Being there several times, if it were me I would postpone till next year when it would be way more enjoyable when the weather is warmer. I have gotten wet by the mist (felt like rain) while walking on the canadian side. Not fun when it is cold.
What about going south and doing Luray Caverns, Natural Bridge, Blue Ridge Parkway, Shenandoah Valley etc. The scenery with the changing leaves will be beautiful and there are areas that you stop and take a small walk/hike to see.
One more thing if you decide to do Luray Caverns. make sure you have a Giant Bonus card it seems to be the best deal
From the luray caverns website. (not in the most visible place)
There are a number of discounts available. The ticket office has complete information, but some of the most popular include*:
AAA membership discount $2.00 off each adult admission (up to 6) with your membership card
Ukrop's Valued Customer card $4.00 off each adult ticket (up to 6)
Giant BonusCard one 50% reduction off a second regular adult ticket
Participating companies and military bases (through their Human Relations Department) $4.00 off adult tickets
* Each of the above is not applicable with any any other discount. Discounts are only valid when purchasing tickets on-site.