Here is a lovely get away to Stockholm for 2 nights in April staying on a boat. Leaving on 20/04 and returning on 22/04 you'll have 2 nights/3 full days to explore Stockholm.
I've picked a boat accommodation, the MS Birger Jarl which is on Sodermalm which is easily connected with other parts of Stockholm via Slussen metro. There are plenty of good restaurants and bars nearby and it's easy to get around Stockholm. The Vasa museum is well worth a visit and certainly "take a chance" on the Abba museum (see what I did there)!! https://www.tripadvisor.co.uk/ShowUserReviews-g189852-d4737376-r380233528-M_S_Birger_Jarl_Hostel_Hotel-Stockholm.html
The boat accommodation has private bathrooms and includes breakfast too which is a great deal as food can be quite expensive in Sweden.
Book 2 nights on the MS Birger using code AFFVC0317 £88.74 http://ebookers.com
Book 2 return flights £67.96 http://ryanair.com
+ Transfers: 556kr for 2 adults return which is just over £50.
Flights now £ 93.96