What a great itinerary, been to all of them but Bergan.
Here are my thoughts on some of the things I've done on the several times I've been to these.
Glasgow - While the "Loch" options are very tempting, Edinburgh is a lovely city. Edinburgh Castle a must, Holyrood Palace. Very nice and interesting. If they offer the tattoo (you should be there while it is going on), I"d take it in a heartbeat, haven't been able to do it myself.
Rotterdam - head to Amsterdam, take a canal ride, stoll the streets, hit the flower market. The Anne Frank House, if you don't go thru it, at least go by it.
In Brussels/Bruge (Zeebruge) - go to Bruges, oh my such a beautiful 'Venice Like' city, absolutely beautiful and make sure your tour includes a canal ride.
For LeHavre - Paris highlights is enough, but after several trips there, I opted for the tour to Versailles and was not disappointed, absolutely spectacular.
In Dublin - been there several times, an easy city to do on your own if you can walk. Stop in a local pub and have a brew, make sure you see St. Patricks Cathedral where Jonathon Livingston Seagull is buried, Trinity College. If time permits take a tour out into the country side, one that may include Malihide castle, enjoyed that one very much.
We are from England & did a round Britain trip on the Golden Princess last year, and thoroughly loved every minute of it. You say that you are travelling in August, but there are 3 trips on the Golden in August, if you let us know which one are you on, we'll do our best to give you as much information as we can.
We try & check this site every couple of days, so will keep an eye on this message for any of your details and questions.
The ship goes to Dublin, Glasgow, Bergen, Rotterdam, Bruges and Normandy. We were thinking of going to Edinburgh instead of Glasgow (not much to see in Glasgow??), Delft (since we've been to Amsterdam more than once), Brussels (never been there) instead of Bruges since we can only pick one, and Normandy beaches (been to Paris more than once and really want to see Normandy).