There isn't much to see in Dalian, except perhaps the boundary between Bohai and the Yellow Sea. When conditions are right, you can see where the waters meet. Then again, your cruise may well sail across it.

Qingdao has an unmistakably Bavarian feel, but it isn't something worthy of going out of your way for. But since you will be there, just walk around the older parts of the city where the short presence of the Germans left a permanent impression. Much of them are newly restored and not original, however, because the proletarian cultural revolution of the last century didn't take kindly to those relics of imperialism. I would definitely tour the Tsingtao Beer brewery.

Basically, Dalian and Qingdao began as foreign trade concessions, with no significant roles in Chinese history before the last ~150 years. And unless you like sea cucumbers, of which there are plenty and in very good quality, neither Dalian nor Qingdao have noteworthy local foods. (And in case anyone asks, yes you can bring sea cucumbers back to the U.S. -- just declare them on your form.) Other than that, the air in both cities is great, so feel free to breathe. And the people are friendlier than anywhere else in China that I've been to.