We go every year for T-giving, and frequently in Jan.
Crowds in the parks are MUCH lower in Jan (at least after you get past the NY holiday)...marathon weekend can be a bit crowded (and I'm told MLK Day week can be, too)...but generally it's a "low crowd" time.
T-giving is crowded...it's the time of year when we most value being
DVC...we usually get to the park around-about when it opens (DS and I "fight" (gently) about this...I see no difference between waiting in line for a park to open as compared to waiting in line for a ride in the park...he likes rope drop...so one day we do it his way; the next mine--I like to try to time arrival for 5-15 minutes after the park opens)...usually the parks and waits are fine til around 11 or so--after that, they get steadily busier as the day wears on...by mid-afternoon they're more crowded than we like.
So, we do our rides in the first couple of hours--frequently return for an ADR (we particularly like the Epcot restaurants), but whether we ride anything is hit or miss, depending on wait times...
We don't tend to do late hours because I'm not a late night person...I'm much more an early morning person...and DS is in school so T-giving week is his "R&R" time...he sleeps a lot--on a beach or by a pool or on a park bench!
Anyway...we LOVE T-giving at Disney--but definitely not for the rides...it's too crowded for our tastes for riding rides. But we love the decorations, the atmosphere, the restaurants, the just hanging out in parks or pool side or in Downtown Disney or on the Boardwalk or wherever our fancies take us...
Enjoy it whenever you go!