Canberra isn't so bad. Really. Everything you might need is either on campus or a 15 minute walk into civic - that includes doctors, newsagents, supermarkets, movie cinema, bookstores, pubs/bars/clubs, etc. People say that it is dull, and I suppose that's quite true, but when you live on campus alongside about 4000 other students, there are lots of things to do. Colleges have about 4 events per week, and your best friends are only down the hallway. The buses are actually fairly reliable too and it is a good place for riding a bicycle because it is so flat.
I've done a lot of social sciences, and ANU is a really great place for it. It's in the capital, so a lot of policy work gets done in Canberra. I've heard rather mixed things about the economic lecturers, but there are a lot of good social sciences lecturers, particularly in later year subjects. A few times I've had lecturers who have written 20 books on the subject they are lecturing and they are usually really engaging. Not always, of course there are dull boring lecturers too.
If you book online and early, you can get a bus to Sydney for $15 and lots of people from Sydney bus/drive back for weekends, particularly long weekends. In all likelihood, you could make a friend from Sydney and stay with them, or at least get a lift from them. You can also fly to Sydney relatvely cheaply, but I think the bus is a better option because there's less messing around at airports. The bus station is in walking distance from the uni.
I personally quite like UniLodge, and they do have people there for pastoral care and for organising events and such, so it's not unlike 'traditional' halls and colleges. And the fact that rent is actually going down next year makes it a really enticing option, and in fact I've applied to move there. The other halls are really good too. Realistically, all the halls offer pretty much the same things at comparable prices apart from Fenner and B&G being self-catered only. I think you can be happy in any of those places, but most people say that for catered, Burgmann and Bruce seem to be the best. I'm not sure whether or not it is true.
I'm in the Burgmann postgrad village this year, so I have some experience with self-catering. Restaurants in Canberra are by and large quite expensive but there are some really awesome cheap ones too like Asian Noodle House (they have awesome laksas) and Happy's (Chinese food mostly). I usually go out about once a week and probably get lunch in union court once or twice a week, the rest I prepare in the kitchen. I probably spend $25-$30 a week on groceries just for me and probably another $25-$30 eating out. I eat mostly pasta, minced beef, chicken, steak and rice and vegetables like spinach, onions, potatoes, tomatoes, etc. This option is much cheaper than catered accommodation.
ANU is a great university, but particularly for research. We are ranked top in Australia according to some rankings and second according to other rankings, so it's really up there. As a graduate, your employment prospects would be pretty much the same as a Sydney/Melbourne graduate. The average starting salary for an ANU graduate, I believe, is about 44k.