I grew up in the 'Couv.
It's right across the Columbia River from Portland and is that city's largest suburb. Population of Vancouver is roughly 150,000 plus almost another 100,000 in nearby outlying areas (Clark county).
That's a very poor picture of its downtown, btw, but don't expect much more. Being basically a bedroom community for Portland, Vancouver doesn't have much of a downtown and, for most of the folks there, it's just a place to live. The night life and fun is all over in Portland (which isn't bad).
Seattle is 160 miles north up I-5. Contrary to popular belief, btw, the city of Portland is almost as big as the city of Seattle population-wise. Portland has quite a bit to offer, especially during the summer (when it has the world's greatest weather), and is only 10 miles south of Vancouver.
If you're looking for an apartment, your best bets are Cascade Park and Fishers Landing area on the east side, the Van Mall area in the central north, or the Hazel Dell-Felida-Salmon Creek areas on the northwest (edit: which is, IMO the nicest part of the city, but then that's where I grew up). I personally don't like the Orchards area. For the nice apartments, they run as low as $600 for a small one-bed, $800-900 for a 2-bed, and up to $1,200 for a large 3-bed. There are an abundance of newer luxury apartments, as the area has undergone a huge population boom in the last 10 years. If you're looking for the best place to live, I would stay out of the inner areas of the city or... you should check out Portland (just a thought), but the rents are a bit higher (depending on the area) and you would have to deal with traffic and Oregon state income tax.
Lifestyle in the Portland area is mostly outdoors, especially in the summer. The Cascade mountains are only a hour east and the Pacific ocean is only an hour west. The city of Portland has constant festivals all summer long in a large park on the downtown bank of the Willamette River. And then, of course, there is the 2-mile-wide Columbia River and its beautiful gorge through the Cascades to the east.