So I've spent a bit of time creating a new transit map showing the entire GTHA. It was wayyy too big to be posted using the photo uploader here, so I had to upload the jpg onto my personal website. It's available here:
http://www2.andrew.thejohnsonclan.ca/GTATransit_NTS.jpg
A few things to note about it:
1) I've developed a new naming system for the entire region, to ensure consistency. Each route is lettered and then numbered. The letter prefix tells you the route type, while the number distinguishes it from other routes of the same type. E = Express Rail, S = Subway, L = LRT, B = BRT. Also, although it is not expressly denoted on the map, but solid lines represent more 'local' routes, while lines with a stripe down the middle denote more 'express' routes.
2) I've based the system heavily around Express Rail (think S-Bahn). I envision the lines running 15 minutes off-peak and 5-10 minutes peak, depending on the lines. Unlike the current GO system, which has them set up as independent lines, I have linked the Milton and Stouffville lines, as well as the Georgetown and Richmond Hill lines.
3) The DRL: Probably one of the most radical changes on here compared to other maps is the DRL. Because the system relies so heavily on E lines, I figured that full subway capacity would not be needed for the DRL, as now in essence there would be 4 different DRLs (E1, E2, E3, E5). This allows the DRL (referred to on the map as the Jane-Queen-Don Mills LRT, or the L3) to run in-median on both Jane and Don Mills north of Eglinton, and run in a tunnel south of Eglinton.
It also interlines with the current route of the Queen streetcar, which would share the same tunnel as the L3 (under the route name L4) from Roncesvalles to just after Broadview. Beyond that on both sides it would use in-median LRT, with the west part being the routing of the WWLRT from TC.
Using LRT technology for the DRL provides for much greater flexibility in terms of operating environment, and allows it to extend to Steeles West Stn and Seneca, something that would have never happened if it was using subway technology. The E lines would bring the predicted ridership down to a point where tunnelling was still justifiable, but that HRT was not absolutely needed.
4) Eglinton LRT: The biggest change of the Eglinton LRT (L1 on the map) is the extension into Mississauga. It runs in the same corridor as the Mississauga Transitway to MCC, and then interlines with the Hurontario LRT (L5) to Cooksville. My rationale behind this interlining was that the stretch between MCC and Cooksville would be the heaviest used portion of that line, so interlining the L1 and the L5 boosts frequency on that section, without having to add extra trains or do short-turns and stuff on the L5.
5) Regional Rail (R Lines): I've created a new type of service that goes from the terminus of the E lines to nearby cities in the GGH. They're regional lines, or R lines. Basically what I envision for these lines is Ottawa O-Train style DMUs running at around 30 min-1hr frequencies (higher in peak) running on non-electrifed tracks between the terminus and that nearby city. The ridership demands wouldn't justify Express rail, but these type of trains I think are about the right mix of capacity, frequency, and cost to make the services viable. Berlin does this, where they have these type of DMUs that run from the far flung cities into a major suburban transit node, where people can transfer onto more frequent and higher capacity services.
If you have any more questions about why I did what I did, just ask.
also with this design, only 1 new light rail line 
