One thing that United provides on their site is that on the status for my flight, it includes a link for "where is my plane coming from?" And you can track the status of the particular aircraft that you're scheduled to be on, two or three or more flights back. I've not found that for other carriers - flightview and flightaware track things by flight number, but, as far as I know, they don't tell you about a particular aircraft.
(Caveat - yes, carriers can change aircraft as circumstances change, but the information United provides is a good start.)
I'm also flying tonight, but Delta's coast to coast flights almost never seem to have issues with late aircraft on the Orlando route. Maybe they keep those planes in the southern half of the country so they can avoid weather.