Getting too few calories has been my concern also and that's why I tend to look for the highest calorie cheese and salad dressing (low carb, of course).
My favourites are bluecheese and bluecheese dressing, but you can find so many different kinds of cheeses if you are willing to explore the shelves!

Cream cheese is another good way to add calories, I use it as a dip for celery and it's delicious