The 6qt is pretty big, but I don't regret it (skinny single girl).

You will have leftovers. If you make chili or curry, you will have leftovers for days and days. Even though I gripe about eating the same thing, it's really nice to have a wholesome meal ready that I don't have to cook. I also plan ahead and freeze some of it, which never fails to save my ass later when I'm starving and there's nothing in the house to eat.

Things that I like being able to fit in the slow cooker: ribs, whole chickens (for broth or otherwise) and corned beef. Large quantities of beef stew and similarly delicious soups. I have a smaller crockpot that I picked up for $5 at a yard sale, and I've used it maybe once, whereas I use the 6qt pretty frequently. If worse comes to worst, I lug my leftovers to a friend's house.

I have this Crockpot brand cooker that I got at Costco (I think it was $27 at the time), and it's been solid. Hasn't broken or discolored at all in two years of moderate use. It tends to run pretty hot, but just like any cookware, you learn to work with it the more you use it.

Edit: I have never once in my life used the "Little Dipper" that came with it, but owning it makes me feel like one day I will be the type of person who has her shit together and makes cute little appetizer dips.