Time4wine

I am from the US as well and my oldest son has lived in the Stockholm area for almost 9 years now and we've been to visit a couple of times. My personal opinion is that is not enough allotted time to really enjoy those specific attractions. The remaining time is probably spent shuttling you to/from the port and between the attractions. Vasa Museum is amazing and we definitely were there more than an hour, as is Old Town (I spent every day there walking the shops), and while we didn't go into City Hall, we did go to the Palace and spent a couple of hours there. It all depends on what interests you. Maybe google the options available and see what is best for your group. July is an absolutely beautiful time to be in Stockholm!