I spent the summer before last in Stockholm for 6 months
Some general points I noted about Stockholm (for comparison I live in London).
Stockholm is quite a small city for a capital and it's very easy to walk around the centre and other areas are very easily reachable via public transport and taxis. Public transport is clean and taxis are easy to find although the prices are similar to London.
Take the ferries! They're often the quickest way to get around.
Hotels are similarly priced to London. Unlike London though, there aren't many cheap food options and most restaurants are around the mid-price range. Supermarkets in the centre are quite small and don't offer much in the way of ready food. As I didn't have a kitchen in my hotel rooms it meant I ended up eating out almost every day which got quite expensive.
Summer in Stockholm is great - there's a really laid back summer party vibe with most locals out in bars and restaurants in the evenings or weekends. Winter I've heard is terribly cold!
I felt very safe in Stockholm when I was there and didn't have a problem walking home at night by myself.
Tourist attractions aren't particularly unique or captivating. Most of my sightseeing time was spent eating/drinking and getting different views of the water, which is stunning!
There's no need for cash as everything can be paid for by card.
Swedes speak excellent English and I had no problems with a language barrier at all.
Stockholm is composed of various islands, each with a slightly different character. I stayed in a few hotels in the neighbourhoods Norrmalm and Ostermalm which is where the wealthy live and where the main shopping areas, clubs and bars are. Expect high street and high end stores along the shopping streets.
I also frequently visited Gamla Stan, which is the old medieval town, because I liked its character and there are quite a few good restaurants and bars there. Kungholmen is more residential and I only visited once to go to an excellent floating bar.
Whilst Stockholm is known to be a little hipster-y, it's the island of Sodermalm where you can see and experience this. There are cheaper restaurants and bars and a noticeably younger crowd.
My favourite island is the Djurgarden, which is home to a huge park and several of Stockholm's museums. The park is well kept and has several garden cafes and it's the perfect place to spend a chilled out afternoon. For a slightly different museum experience, check out the Vasa Museum which is home to a fully intact 17th century ship, and Skansen which is an open-air museum that gives you an experience of Swedish history complete with characters in period dress. There’s also the Nordiska Museet and even an ABBA museum although I didn’t visit these!
One weekend my boyfriend and I decided to experience the archipelago since we'd heard so much about it. Given the weather was a little unpredictable, we decided on the morning to go and took a ferry out to Sandhamn, a mid-sized island that was about 1-2 hours boat ride. We ended up spending very little time there as there was nothing to do... we took the next ferry back. I really enjoyed the ferries though - they were the highlight of that day!
More photos and links to food etc. here https://goo.gl/VXdWp6