Marc,
These guys:
http://www.offroadacademy.com/
are located in the West Vancouver area if you want to check them out for some wheeling stuff. They're LR guys there.
Stanley Park is a beautiful park and very large. The Vancouver Aquarium is there too. Downtown is full of stuff to do so just head there and I'm sure you'll find more than enough to keep you busy but I suggest staying away from W. Hastings at night. It's pretty rough. You'll see what I mean if you see it during the day. At night it's way worse. Other than that, you're ok. Granville Island is very cool, the Public Market there is fun to hangout in. The sea wall is nice too. If you want to do some skiing/snowboarding, you have Whistler Mountain and Grouse Moutain nearby. Whistler is by far the bigger of the two and a world class resort.
Make sure you bring some rain gear with you (light raincoat and a baseball hat or something like that) and sweaters. January/winter is typically rainy season there. They don't get much snow, a little, but mostly rain. It gets rather chilly during rainy season believe it or not. Vancouver is a beautiful city so no shortage of stuff to do. If you want to go whale watching, just head to the harbor and you'll come across something or just walk into any hotel and ask them about it. They'll point you in the right direction. There's also a lot of guiding companies if you want to do ocean kayaking (although it might be a bit cold).
If you rent a car there (I'm assuming you plan to), you can go with a big truck but my experience is a smaller vehicle gets you around better there. Especially downtown area. I rented a little Mitsubishi Outlander when I was there and it was perfect what I needed. Oh yea, it's definitely a LR city. You see lots of them there. Mostly Discos and RR but you do see D90's and D110's around every now and then.
Oh yea, almost forgot, go to Robson Street. There's lots of bars, pubs, shops, etc. there. Very cool place.
This is a cool link if you want more info:
http://www.discovervancouver.com/
Hope that helps. You'll have lots of fun there.