Carol, hope that I am not to late in answering in regards to your request for spinach salad dressings. Here are two that I have made many times, one from a restaurant from many years ago and one from a cooking class that I took many years ago in CT.

Spinach Salad with Hot Bacon Dressing

1/2 pound bacon, diced
1 onion, large, diced
1/2 cup white vinegar
1 teaspoon salt
1/2 teaspoon black pepper, ground
1 to 2 teaspoons sugar
2 tablespoons cornstarch
1 cup chicken broth
1 pound spinach, cleaned, stemmed, dried

Saute the diced bacon until crisp.
Drain and set aside.
Saute the onion in the bacon drippings until translucent.
Add the vinegar, salt, pepper and sugar.
Dissolve the corn starch in the consomme and add to the sauteed mixture, stirring until slightly thickened.
Cook over medium heat.
Return the cooked, diced bacon to the dressing.
Divide the spinach among 4 salad plates and pour on the hot dressing.
Serve immediately.

NOTE:
be sure not to scorch the dressing while cooking.
The dressing can be adjusted by adding more vinegar for a more tart, or by adding more sugar for a sweeter taste.

Dressing For Spinach Salad

1/2 cup onions, chopped
1/4 cup ketchup
1/2 cup salad oil
1 teaspoon worcheshire Sauce
2 cloves garlic, crushed
1/4 cup vinegar
2 tablespoons sugar
1 teaspoon salt
1 teaspoon pepper

Combine dressing ingredients and let sit for at least half an hour.