Loved Porto--beautiful city and so much to explore on foot! A couple of highlights--crossing the river to the old section where the port wine tasting rooms are. There are several, such as Burmester and Grahams Port Lodge. It's been too long since I was there, but the tastings, at that time were either free or very low cost.
You HAVE to see a Fado (some similarity to Flamenco) performance. We prefer the small intimate places where the staff basically comes out from behind the bar or food counter and we are transported to another world, but some people might prefer a large stage. All is good.
I don't know which route you are taking, but if the interior, rather than the one along the coast, you might consider taking a day off and doing a boat trip up the Douro River through the vineyards. We were so consumed with the walking part that we decided to skip this day trip, and I wish we had taken some time out.
Congratulations on your marriage and enjoy your special honeymoon!