One day in NEPA is not enough time to see all the cool RR related stuff. Especially on a bike.(although this time of year is iffy at best)
Ride up one of the two lane roads, like 611. Pass the Delaware River Viaduct and through the Water Gap. Stroudsburg has a restored tower. Follow the former Lackawanna Main over the top of the Poconos. Much of the scenic route is accessible by paved (curvy) roads. Maybe catch a bunch of Alcos bringing a DL freight down into Scranton. Stay at the Radisson at the former DL&W Scranton Station, then in the morning, walk over to Steamtown and enjoy the museum. They have an N-Scale model of Tunkhannock, and lots of really cool stuff.
Grab a few Texas Wieners at Coney Island Lunch and enjoy an evening exploring the Station Hotel. (DON'T try the drink called The Phoebe Snow, The real Phoebe would wretch) In the morning, take a short ride to check out the Delaware-Lackawanna shops in South Scranton. Lots of old Alco Dinosaurs, right next to the road.
I grew up a block from here in the 60s when this was the D&H Penn Division Main and Alcos hauled a$$ upgrade to Ararat, then down under Starrucca.
Then head up the North Scranton Expressway along side the Lackawanna/ Erie-Lackawanna/ D&H/ CP/ now NS. Exit to US 11 N through Liggetts Gap, through Clarks Summit, then you'll be on the old right of way of the DL&Ws original alignment to Hallstead where it met the former Erie line. Follow the road to Lanesboro, passing the former Erie and EL station and passenger car shops in Susquehanna. Continue on to Lanesboro and see the Starrucca Viaduct . Going south on Pa 171 you'll be just west of the D&H route over Ararat, where double headed Challengers hauled coal out of the Lackawanna Valley. At Herrick Center, take a left on PA 670 and head down to Honesdale and check out the D&H Canal museum to see how they used a gravity railroad to get coal from Carbondale to the head of the Delaware & Hudson canal. This is also the location of the first steam locomotive to operate on commercial rails in the United States.
From here you could head east, cross the Delaware and follow the Erie/E-L/ Conrail/NS along the river past some cool railfan photo locations, like Pond Eddy, Mill Rift, and Sparrow Bush, to Port Jervis. If your A$$ is sore by this time, you can find a few nice rooms here and maybe explore some former Erie/ E-L/ Conrail locations.
By now you have a few choices. Take US 209 (The Ho Che Min Trail )back down to Stroudsburg and back the way you came or take I-84
back to Scranton and the Turnpike south.
OR
Drive up to Scranton, check out Steamtown, run up US 11 past Tunkhannock and Martins Creek, up to Lanesboro, back down 81 to the turnpike and be home in bed that night

Greg O