Sweden is very expensive, specially if you intend to drink wine
during your meals (it can be a third of the total price). But, there
is always an option. Instead of making a big meal in the evening, opt
for a set lunch at noon. Many places have set lunches for around 50,
60 SEK (including salad, a drink and coffee), and it is a good way of
saving without having to go to MacDonald´s.
A very nice restaurant, although on the expensive side,
is Gondolen. Perched over a lift, in Slussen, with fine views over
Gamla Stan and the lake. If you don´t eat there, go for a drink
(although probably eating is cheaper...).
You are going to Sweden in a really fine time of the year. There will
be plenty of light, and everything will be in blossom.
Check the URL mentioned by Tuija. It is very useful, and go to the
Sweden House as soon as you arrive, plenty of info, and so many books
on the country.
I love the Wasa Museum and the Nordiska, and also walking along the
Old Town, the parks, the streets.
Have a brilliant time, and tell us everything about your journey,
once you´re back.
Rgds from Covadonga in Bilbao (Spain).