If you are in Stockholm, check out City Backpackers, a big place with a large common room, free coffee, tea, pasta, a lot of computers for free internet. It's very socialable and in a good location with a helpful staff.
Helsinki check out Hostel Erottajanpuisto. It's a nice relaxing comfortable hostel, a little pricey 22 EU in an 8 bed dorm, but Finland is expensive anyway. Its in a good location and staff is really friendly.