Most stations are looking more or less alike, except for the colour schemes of the wall tiles. But TTC's Art in Architecture Program has integrated a considerable collection of public art into the stations [transit.toronto.on.ca].
Photo [Craig James White, flickr.com]: Dupont station from 1978 on the Yonge-University-Spadina Line.
Especially the new Sheppard Line has some interesting stations [city.toronto.on.ca]. Furthermore, the Arts on Track Project aims to revitalize a couple of older stations through donations [tcf.ca].
Photo [Craig James White, flickr.com]: One of the many optical illusions by Toronto artist Panya Clark Espinal at Bayview station from 2002 on the Sheppard Line [haha.nu].
Tours of the metro system, guided by experts. For dates and reservation contact the tour operator or check their website.
Joe Clark, journalist, typesetter and presenter of talks about historic TTC station typography, has hosted guided tours on station tiling and typography in Toronto's subway stations in 2007. He might possibly host more such tours. Tour operator: Joe Clark.
Try the following tour, recommended by residents or metro enthusiasts:
The stations along the Spadina part of the Yonge-University-Spadina line are quite interesting, e.g. Dupont Station and the recently upgraded Museum Station with museum-themed pillars and interesting wall treatments. Ride the Sheppard Line for its interesting stations. Union Station has a small store that sells TTC mechandise.
Lake Ontario: A beach is being "constructed" between the Spadina and Rees stations of the Harbourfront light rail line. Queen trolley line runs within a block of "The Beaches" along the shore east of downtown as well as a block north of the western beaches (Sunnyside, Humber Bay, Mimico, Long Branch etc.) along The Queensway and (of course) Lake Shore Blvd.
The drivers call the station (usually "[Name] station is next. [Name] station.") There is a three-note chime (G, E, C downward) announcing the closing doors (wav from ttc.ca). A new call system with an automated female voice says "Next stop is [name] station. [Name] station." Then as the train decelerates entering the station, "Now arriving at [name] station. [Name] station." The first single note of the chimes is also played when the doors open (G note).
Sheppard-Line train leaving Don Mills station. Video by wyliepoon.