The Christmas Putz in The Lutheran Home at Topton is open Saturday and Sunday afternoons. Admission is free. The address is One South Home Avenue, Topton, PA 19562.
Topton is about halfway between Allentown and Reading at the top of the grade of the former Reading East Penn Branch (now Norfolk Southern). It's an active freight route. The station is now a bakery and deli.
Reading Railroad Heritage Museum, 500 S 3rd Street, Hamburg, PA 19526 (610-562-5513) just opened a Christmas "O" Gauge layout right off Route 61 south of the I-78 cloverleaf. The Reading Company Technical & Historical Society (www.readingrailroad.org) offers tours of Reading locomotive, cars and displays there.
About 5 miles west is Roadside America, last of the great Lionel postwar layouts.
DOWNTOWN PHILLY: Layout in Reading Terminal Market (as Mike mentioned; www.readingterminalmarket.org); ANOTHER in SEPTA Museum, 1234 Market Street; Go East of City Hall on Market Street and enjoy magnificent Christmas decorations in Macy's (formerly John Wanamaker); Follow Benjamin Franklin Parkway and visit The Train Factory (formerly Railroad Hall) in The Franklin Institute (www.fi.edu). Ride in the cab of Baldwin 3-cylinder compound 4-10-2 No. 60000.
Nicholas Smith Trains in Broomall (2343 West Chester Pike - 1 minute off I-476 Exit 9) is well worth a visit.
Board a train to New York City and take the F train to Brooklyn. Get off at Ditmas Avenue. Go downstairs to street level. Walk over to Bianco's Trainworld at 751 McDonald Avenue.
Also take a walking tour of NYC layouts and window displays.