Paul,
I have had 2 great experiences with cruises. The first being a 14 day from Italy to Spain to UK, To Iceland to US. The scenery was breath taking coming out of the Med into the Atlantic, then they hugged the Atlantic coast line to the UK. Then around to Ireland, then unto Iceland around the coastline there and then to NY.
You rarely felt that you were on a ship, ok except for the beautiful view out the deck of the cabin.
We did take a few of the offered tours, some times we took off on our own.
We hit the duty free shop, and stocked up on the alcohol of choice. Prices were a little higher than average for the cola and on board liquor. Our cabin stewards were very helpful, in making sure everything was good.
You might see if they offer an all inclusive plan.
My second cruise was a 12 day Hawaiian Isle cruise. We upgraded to the all inclusive plan and it was worth it. I do remember the one bartender on board who made a wicked Mai Tai, and when he found out we had upgraded, HOLY COW did those drinks have RUM In them!!
That cruise we were rarely 5 miles from the coast most of the time 1-2 miles off the coastline. Which offered some beautiful sunrises and sets.
The cabin steward were again extremely helpful, even at 2 in the AM when we broke the bed

, we called and less than 10 minutes later they were there to replace it.
The laundry service on board was not too bad price wise, those durn little tags they ironed into your shirt scratched though.
Paul, I think your trip sounds like the adventure of a life time. If you are used to being in a hotel, then the cruise is not that big of thing. It's like being at one the huge places in Vegas, with all the rooms, and places to eat and things to see and do.
I am envious Paul, that is one of the things I have always wanted to do, sail around the cape. There are 6 things on my list of must things to do.
1. Cruise from England to US - DONE
2. Cruise around S America
3. Cruise the Panama canal
4. Make a 1 trip round the world journey - DONE
5. Visit the pyramids in Egypt
6. Visit the Great Wall of China
Go FOR IT PAUL !!!!!