Nomads is an amazing place to stay to meet new people and socialize. It is a very central location and has lots of cheap and accessible amenities (ie you can rent a surf board for 10 bucks a day). I highly recommend staying here!
I really enjoyed staying at USA hostels in Beverilly Hills. The staff were awesome and the environment was great.
Sant Jordi Alberg is the place to be in Barcelona! It's location is very central being close to Catalunya at Las Ramblas along with some of Gaudi's most famous works. Goncalo is the man, he takes you out to the major bars and clubs on a nightly basis showing all that the city has to offer. The hostel itself if very clean and homely with a nice lounge for meeting people. Also they have a fully equipped kitchen for those of you who like to cook your own food. Stay here! Its the place to be!
Tiger Tim's provides one of the most homely hostel experiences you'll have in Europe! The staff are extremely friendly and helpful for taking in the city of Budapest. On a nightly basis you get together to play drinking games and all go out together to the best local bars and clubs in town. This hostel gives you the chance to see more than the simple tourist traps that most travellers end up at. I would highly recommend staying at this hostel for comfort and fun!