Stockholm suggestions

Not sure what you will do on your tour but the places I liked:

Gamla Stan--Old town--just wandering

The Royal Palace

Skansen--the world's oldest open air museum with a zoo and aquarium.

Vasa Museum

Cruise on one of the canals or on the lake.

I made my second trip to Stockholm last month.

Drottingholm Palace where the Royal family lives. Lovely grounds. Take a boat across the Lake Malären to get there.
Take a boat out in the archipelago to Fjäderholmarna Island for lunch.
Visit outdoor sculpture garden Millesgården, home of sculptor Carl Milles. Beautiful setting on the water.
ABBA Museum is near VASA.
Skip Skansen.
Swedish friends gave us the above places to visit. Fjaderholmarna was a unique experience.
We stayed on Djurgarden, easy to get around from there by ferry or foot.

If you want to sketch, there are great views from either Fjällgatan or Monteliusvägen.

I also don't know what is included in the tour and what you are interested in. But you have recieved some great suggestions.

Apart from those, Djurgården is not only home to a number of great museums, it is also a lovely place for a walk if the weather is nice. The local ferries are also a great way to see the city from the water at a cheap cost. Or watch the changing of the guards at the palace, or at least catch the parade. There are also a number of great museums in Stockholm if you are interested.

Or you can spend the extra day in Uppsala, that should in my opinion not be missed if you're visiting Sweden.

You can find Rick's suggestions on this website at Explore > Sweden > Stockholm > At a glance. I doubt that the tour has time to cover them all--there are 19 places/things listed.

Jen,
The Vasa Museum is included on the tour, an absolutely fascinating place! I had 3 days in Stockholm before the tour began, so I would suggest Djurgarden, a beautiful park with the Vasa Museum and others. We didn’t go to Skansen because my friend insisted on going to the ABBA Museum which we found underwhelming. A tourmate went to the Nordic museum which she said was interesting.

Another tourmate said they went on the boat tour under the bridges I think it was called.

Wander around the neighborhood of the hotel and find the Food Hall which is very well known. It’s called Saluhall. You can ask at the hotel for directions, it’s an amazing collection of cafes and food stalls offering wonderful seafood, pastries, meats, vegetables! What is your hotel in Stockholm?

You will love this tour! I did.

I didn't love Skansen. I might have liked it more if I'd arrived later and planned to stay for the traditional Swedish dance/music performance. We had planned on leaving about the time it started.

I did love the Vasa. The ship isn't from my favorite historical period, but I really enjoyed the preserved state of the ship.

Will you see the archipelago? That was one of my favorite things to see. It stretches quite a distance from Stockholm. Perhaps you could catch a ferry to one of the islands and see some of it during your day?

Again, to see some of the archipelago, take a boat to Fjäderholmarna from the central waterfront. We had lunch there and enjoyed the journeys both ways.