1.
The beaches are clean and uncrowded. The surrounding countryside is lush and soothing to winter-weary eyes. Furthermore, being able to take sailing and scuba diving lessons, while friends back home shovel snow, makes the outdoor activities extra-enjoyable. On the other hand, several features of Club Tropic are substandard. Security could also be better, as thefts from several guests' rooms indicated. So for some vacationers, nice scenery and fun activities may not be enough to offset the possibility of poor service and lax security.

What would be a good topic sentence to add to this passage?

The lock on the door is a joke because it can be opened using a credit card.
The morning mist from the far off mountain is a beautiful sight to weary eyes.
The food is poor, and, because the club is isolated, eating elsewhere is impossible.
A midwinter vacation at Club Tropic has its good points and bad points.



Answer :

Most likely: "A midwinter vacation at Club Tropic has its good points and bad points". 

It sums up the basic points of the paragraph, and introduces the subject in a more or less general way. And by placing it at the beginning of the paragraph, and reading it out loud or in your head you can see/hear how it suits it.

Answer:

A midwinter vacation at Club Tropic has its good points and bad points.

Have a good day.