Initially we thought a Folkboat might be nice and fit in with a Swedish theme. Then we started to think that headroom, and a shower and large water carrying capacity would all be useful and not available on a folk boat.
After considering all the factors a Bavaria 42 seemed to be the absolute minimum size that two people can comfortably spend a week on.

We started from Gashaga Marina and did a sort of ad hoc following the wind loop.
Route here:
http://tinyurl.com/3xfmcsa" onclick="window.open(this.href);return false;
Seemed a pretty good place to go sailing to me. Absolutely beautiful. Friendly people. Loadsa shelter if you want it.
It got a bit busy but 22,000 Islands give an abundance of sheltered spots to spend the night alone. Also there are various 'nature harbours' which are basically recognized remote anchorages that make it into the pilot books and attract a few more people. (Typically you moor bow to the rocks to protect your rudder but many have space to swing as well.)
No tides, mostly sweet fresh water (mostly you can drink and cook with it).
Weather seemed just like the UK but we had no days with zero wind. No idea if that's typical.
Images here (with a couple of Stockholm itself):
http://fattie.freehostia.com/Baltic/" onclick="window.open(this.href);return false;
(Note: If you look carefully I think I might have got a shot of Webbie and the Scarlet Clergyman on their secret trop to Stockholm.)
Tagged a day in Stockholm on the end and saw the "Vasa". Absolutely blew my mind. Well worth a visit, I thought, and if you don't know the story well worth looking it up.
For anyone interested, images of that here:
http://fattie.freehostia.com/Vesa/" onclick="window.open(this.href);return false;
Not quite up there with Nick's recent epic but still tough returning to work...