The shopping in the main street is superb. Without doubt best quality and value on the med. Prices in Portugal are about 20% less than Italy/spain/France etc. Lovely cafes on the main street and side roads.
Check out a Segway tour of Alfama that some cruises do. It is great.
Lisbon is unique amongst European tourist cities, very very few street vendors selling fake prada handbags and fake rayban sungasses for e25. Most street vendors are licensed and only sell arts and crafts.
If you like football, Benfica do a daily tour of Stadium. It is excellent, it includes lunch and you get the opportunity to fly their club Falcon in the stadium. If overnight, go to a match their or at Sporting Lisbon. They also have Belennses, who stadium, located near the port is small but very picturesque with a semi open roof with your seats facing the port
The port is where you dock. No shuttle bus required. They completed a major port renovation 2 years ago. Small shopping Mall next to the dock, main shops about 5 minute walk.
Some cruise lines do a rafting trip near Vigo. Royal Caribbean & Celebrity use a very good, well organised company, English speaking, helmets, safety vests and full instructions. Instructor on board each raft which has 8 - 10 on board. Great fun, not too strenuous. Hardest part is carrying raft about 50 meters to the water! On our group, a couple of rafts did capsize but instructors had everyone back onboard in a minute. River has quite safe rapids with long stretches of very cool slow moving water to get people back onboard safely. Nice to swim in and cool off. Spectacular scenery. Not suitable for kids under about 18.