Hoping to go to Scandinavia for the first time for one week in July. Would like to go to Copenhagen and Stockholm for sure. After that, wide open. Should we explore more in Sweden or go to Helsinki or smaller towns?

If you've only got a week, then Copenhagen and Stockholm will be enough. Three days in one and four in another. Maybe a day trip from one place, but I wouldn't recommend adding a third city to such a short trip.

Copenhagen and Stockholm - with their suburbs will keep you more than busy for just one week. And, IMHO, Helsinki is not nearly as interesting as either one.

Have you researched the sights you want to see in each place - and calculated how long it will take you to see them?

I have been in Helsinki 45 days the summer 2010 and been sailing by the archipelago 10 days, visiting cities and moving around Helsinki by walking and by tram, some days. For me it's a nice and relaxing city full of quite good cultural life, (at least the design). But I think 6 days for to visit three cities is not enough. I would rather use one week to visit One city just if I want to keep a good taste of it.

Enjoy!

4days in Stockholm, 3 days for Copenhagen would work well.

I agree with HappyTrvlr. Stockholm deserves 4 days. We did the opposite: 4 days in Copenhagen, 3 in Stockholm, so I am basing my suggestion on personal experience.