I loved Stockholm! It's true what they say, your wallet will get a proper bashing, but it's worth every penny. If you drink, buy your alcohol in duty free before you go. My favourite places were Riche (if SATC filmed in Stockholm, they'd film here), Marie Laveau, Under Bron, Rosendals Tradgard, Acne and Marimekko. Top tip: buy food in ICA Supermarkets; cheap and delicious, leaving you with more money to spend on shopping!
We stayed at Hostel Stockholm (booked through Hostel World). Hostel Stockholm is as clean, stylish and slickly run as any hotel, but with the benefit of your own kitchen to prepare your supermarket delights. We opted for a four-bed dorm, paying a bit more to have the place to the three of us. We had an en-suite bathroom. The staff are friendly and helpful (even booking our table at Marie Laveau and organising taxis) and there's a strict 'no booze' policy, you don't have to worry about drunken teenagers.