What to do in Sweden with pre-teen kids
 

I am planning a 2-week trip in July with my husband and 2 daughters (ages 10 and 12). I have ancestral family there to visit but I also want to build in lots of interesting sites and activities especially for my kids to enjoy. What are some don't-misses? (Anywhere in the country -- between the time and the family, I think we'll be all over the place!).

I've only been to Stockholm:
The Vasa Museum
Skansen Open Air Folk Museum
A boat tour of the archipelago

I agree with what abram says. Vasa Museum is quite something for families. But it certainly depends on what you mean by "interesting sites and activities" as you mention that the focus should be on what your kids might enjoy. I'd say get out travel guides and talking it over with them along the way. Youngsters that age can get bored pretty quick!
Bill in Missouri

I'm also planning a similar trip with 2 sons (18 and 12) around the same time, so would also be interested in sites and activities as well as places to stay that are affordable for 4 people. We like historical sites, etc. Thanks.

I recommend that you only spend two or three nights in Stockholm if budget is a concern. Not that you couldn't spend two weeks in Stockholm and you'd still not see it all. But I paid less for a beautiful 3 star hotel in Orebro per night than I did for the 2 star in Stockholm that had the bathroom down the hall. This was June 2002.

In Stockholm I stayed at the Columbus hotel (www.columbus.se) It's in Sodermalm, to the south of Gamla Stan. I walked it several times. It's probably under a half mile one-way though one of the ways is up hill. To help with the budget maybe you could get an ensuite room for the parents and a dorm room for the kids.