You don't provide enough info for people to help - mainly dates of travel. What domestic routes have widebodies can vary throughout the year based on changes in domestic versus international demand and even changes within domestic demand (example: PHX sees some widebodies during the winter/spring months due to higher demand for winter travel to PHX). You probably aren't looking at any one-stop options unless SEA-ATL is running a widebody on the day of your travel. SEA-MSP and SEA-DTW used to see widebodies on occasion but it's been a while since I've seen a widebody on either route. LAX-ATL usually has widebodies so yes, you could probably look at an SEA-LAX-ATL-ALB routing but it may not be cheap (and may be a broken fare). JFK doesn't have service on DL to ALB so that's not an option, even if you routed via SFO or LAX for a true D1 route.

If you really want a widebody, your best bet is probably UA and going to either LAX, SFO, or DEN first and then to EWR** or IAD with of those options on a bird with lie-flats than then allows you to connect onward to ALB. LAX/SFO/DEN-ORD also see widebodies and you can connect onward to ALB from ORD on UA.
(**EWR-ALB service is ending in late March so depending on your travel date, this may not be an option either).