I've really thought about doing the ports on our own.  We are experienced travellers who've been to Europe many times (7 trips!), but only twice with our 3 kids.
This trip is pretty big for us as we are also going to be in Dover 3 days precruise and London 12 days post.  There is so much planning and organizing and doing on our own in London, that just for sheer convenience and lack of stress we are going to go with all 
DCL.  I want a variety of different types of activities on all the ports so the kids don't get too museum and bus weary. I feel really good about all our choices and since I had budgeted $6000 for the 5 of us for excursions, what we want to do works out to $5710 so its within our budget!
I'm still fussing a bit about the whole bathroom bit.  I have euros, but I didn't really want to get any currency for the countries that don't take euros as we really never buy many souvenirs and I had to exchange an unknown amount of money for no reason.  If we see something we like, then we'll probably just use a credit card, or if there is an ATM handy, go there.  But I don't want to exchange money in advance.
The problem is...what about bathroom breaks?  Some of our excursions are all day (most of them are anyway).  Surely we need to use the loo!  Will we need to pay for that ourselves?  We were in Portugal and Ireland for 6 weeks last year and I didn't pay for a bathroom anywhere and we went to many, many, many museums.  I'm going to go with the assumption that the museum loos are free.  If not, well, 
 
Anyone else have thoughts on the loo situation?
Our DCL excursions are:
Copenhagen:  City Highlights and Open Air History (7 hours)
Helsinki:  Porvoo and Helsinki highlights (7 hrs)
Olso:  Norwegian Adventure (3hrs)
Berlin:  Sights and Sounds (12.5 hrs)
Stockholm: Best of Drottingham (both my dh and I are in theatre.  This looks amazing!)
St. P: 1.  Catherine's palace in Pushkin (4hrs)
2. Hermitage and Peterof (9 hrs)
Also interested in the Leeds Castle in Dover!  Relaxing way to get back to London!