To all fellows from Ontario, CDN

Algonquin park is beautiful. There is a river gorge... I can't recall what it was called but look through tour books fore the word "Gorge" and you shouldn't go wrong. In winter, though? Might be closed, or treacherous. Take a guide, if you can.

As to your tour plan, sounds good. Ottawa is fairly interesting, as are the Islands.
Where are you staying in Toronto? What kind of attractions/places are you into?

Send me a PM and I'll spend some time looking up attractions for you when I get home.

Wow, where to start? It really come down to what interests you. Your prospective route covers a lots of geography so I will make some suggestions along that path.

Toronto:

CN Tower, Hockey Hall of Fame, Casa Loma, ROM, AGO, performances at Thomson Hall/the Royal Alex/Princess of Wales/Hummingbird Centre, St Lawrence Market, The Eaton Centre, The Science Centre, Toronto Avation Museum.....

North of Toronto:

McMichael Gallery in Keinburg (might be the largest collection of Group of Seven works in the world)

Towards Niagara Falls:

Niagara on the lake and the Beamsville area have some of the most productive wineries in Canada. Depending on the weather, the Ice Wine harvest is usually in January and all the 50+ wineries have stuff going.

The Niagara escarpment is a ridge that extends from Queenston in Niagara all the way up to Tobermory. Lots of trails (and ski hills) along the way.

Algonquin:

If you are coming from Toronto you'll likely go through the Muskoka area. Lots of historical places on the big lakes (Joseph, Rosseau, Muskoka). The area has been the summer playground for Toronto's elite for about 150 years. I don't know what will be open/accessable at that time. If you are into older wooden boats, the Grace and Speed museum in Gravenhurst is pretty cool. On the same spot used to be Ditchburn Boats (with Greavette to their right) that produced those beautiful wooden boats for touring the lakes.

Algonquin park itself is beautifiul and huge. Most of what anyone sees is the little bit above and below highway 60 (that runs through the park). I know that you can book heated yurts on some of the campgrounds and there are ranger cabins in the interior. We found the logging museum at the east gate interesting as well as the Gallery in the park. If you want to see wildlife, drive "the circuit" along highway 60 and up the road to the Opeongo Store early in the morning and near dusk. If you can bring yourself to spend it, dinner at Killarney Lodge is very nice.

Thousand Islands:

I am not sure that I would make the drive at that time of the year. The homes/summer places to see are all water access and I doubt that the ferries are running then. Too bad through, it is really something - Especially Boldt Castle.

Everything I have noted has more details online. Just Google them and enjoy your trip.

I would suggest that you check stuff out on the web before cancelling anything, like the Thousand Island area. I have only been in the summer and don't live nearby.

Ottawa has lots of stuff too, again depends on your interests:

Parliment buildings (our national givernment), War Musuem, Aviation Musuem, Museum of Civilization, Rideau canel (if it is cold enough you can skate on the canal from the Chateau Laurier/Parliament area down to Dow's Lake. They sell hot apple cider and Beavertails (flat, doughnut like treat) right on the canal. You'll be too early for Winterlude but there should still be plenty of holiday decorations still up at that time.

Google Ottawa and you'll find lots of choice.

I take it you are flying Lufthansa or Air Canada from Frankfort to Toronto. If you could, It might be better to fly into Toronto and flight out of Ottawa (or vice versa) - that way you aren't backtracking. It will be 4 hours plus to get from Toronto to Ottawa by car. It looks like if you connect through Montreal, for at least one leg of your trip (Ottawa to Montreal to Frankfort) it might be a cheaper fare and would save you the extra for the rental car driving back to Toronto. Hertz, Avis or any other the rental car places will let you pick up in Toronto and drop off in Ottawa. You just have to book it that way.

Quick tip: check out Kingston - it's on the 401 on the route to Ottawa. Not sure what's there to see in winter, though. Hmm... not much between Toronto and Ottawa, other than a nuclear power plant and I don't think they give tours. . You might want to do the trip in reverse - Toronto, Muskoka, Algonquin, Ottawa - back to Toronto.

If you are in Ottawa you can also check out Gatineau park just across the river in Quebec. It is beautiful all year round and has some great hiking trails. They have a great zip line tour as well.

Here is a link to a great park that should have a lot of the sites your looking for. Its only about 35 mins north of Ottawa.

http://www.aventurelafleche.ca/en/index.php

Well, I'm home. Insofar as exploring the city, you may want to walk one day and take out a TTC day pass the other two. Now, public transit here isn't as good as in Europe (I was in Austria ages ago as I have family there and I must say the transit in Graz and Salzburg are fantastic) but it'll get you around for the first three days so.

If you stay somewhere, try to find a place downtown-ish, to facilitate walking, or at least somewhere on the subway line. Areas to walk/shop:

Yonge Street (lots of wierd little shops, a huge shopping mall between Dundas and Queen Streets)
Yorkville (Upclass, a bit pricy. Very nice though!)
Bloor Street Annex (Bloor Street between Yorkville and Bathurst Street, a bit more counterculture... if you make it as far as Bathurst check out Sonic Boom, it's a great used music store)
Beaches (Or "The Beach", depending on who you asked. Nice neighborhood with shops in the east end, but more popular in the summer)
High Park (Big park. Nice to walk in.)
The Lake (Is one of the largest freshwater lakes in the world, and there is lots of good waterfront parks, quays and so on. Also, lots of bad ones too. )
Typical Touristy Things (You know, CN Tower, Skydome, Hard Rock Cafe...)

This just scratches the surface... and this is just in the city. Is there anything you or your fellow travelers are looking to do/see in particular? There's a fashion district, for example.

EDIT: Oh, just for clarification, the suggestion to take the TTC is because downtown, parking sucks. Really. A lot.

No problem. As I said though, uptown (North York, Scarborough) wouldn't be too bad either if you're near the subway line - unlike our public transit buses, the subway is actually not that bad and is the quickest way downtown.

And yes, definitely check out Sonic Boom! While you're there (Bloor/Annex area), you might want to walk to Kensington Market- it's maybe a 20-minute walk south-ish. There's a great store specializing in vinyl there, and lots of little, quirky shops and restaurants.