I just marinate in italian dressing with a little extra garlic and some fresh lemon squeezed over it.

Angelaid's suggestion for dressing/marinade sounds about right. In addition to red kidney beans and garbanzo beans, add some chopped red onion and defrosted green beans. I've also seen yellow wax beans added in. Basically, I think anything goes.

a simple vinegar and oil dressing will work, fine.

3/4 cup sugar
1/2 cup cider vinegar
1/4 cup canola oil
1/2 teaspoon salt

Mine is kind of old timey from the 1970s.

1 can green beans
1 can wax beans
1 can kidney beans
1 can lima beans (I never used them because I don't like them)
1 bell pepper, chopped
1 onion, chopped
1 cup chopped celery
2/3 cup vegetable oil
1 cup sugar
1½ cup white vinegar
1 Tbsp. salt

Drain and rinse all beans Mix with onion, pepper and celery. Mix oil, sugar, vinegar and salt in a saucepan. Heat until sugar dissolves. Pour over bean mixture and refrigerate. Serve cold. Serves 12.

I found a lot of variations on the bean salad. Planning to take one to a picnic in a few weeks. I've kind of settled on this one since it sounds so simple and is a little different.

Easy Bean Salad
Recipe by: Kathi S. Yield: 12 servings Ready in: 10 mins (10 mins Prep - Cook)
"An easy, delicious cold bean salad. A big hit at barbecues and picnics! Use any combination of beans you like."

Ingredients (Note: 400g=14.1oz)
1 (400g) tin kidney beans, drained and rinsed
1 (400g) tin chickpeas, drained and rinsed
1 (400g) tin cannellini beans, drained and rinsed
1 (220g) tin water chestnuts, drained and chopped
175g (6 oz) shop-bought tomato salsa
2 to 4 tablespoons French dressing
salt and freshly ground black pepper to taste
Preparation method In a large bowl, toss together the all ingredients. Cover, and chill until serving. Tip: Make your own vinaigrette for this salad if you don't want to use shop-bought French dressing!

I also thought a can of corn would go well (it's included on some), perhaps some onion, celery and/or radishes or whatever else I can think of. Maybe some other beans too like Great Northern, possibly green or wax and even some broccoli or cauliflower florets would go good in it. Seems to be a pretty flexible recipe and should work well at a picnic.

Also there's a couple others that were interesting. Sweet and Savory versions and the Maryland Summer Bean Salad got my attention too.

Here's my old recipe, which is very good.

Three Bean Salad

1 - 1 lb. Can cut green beans
1 - 1 lb. Can yellow wax beans
1 - 1 lb. Can red kidney beans
½ cup minced green pepper
½ cup minced onion (or green onion)
½ cup salad oil
½ cup cider vinegar
½ cup sugar
1 teaspoon salt
½ teaspoon pepper

Drain beans; place in glass bowl. Add green pepper and onion. Mix oil and vinegar with sugar, salt and pepper. Pour over bean mixture; toss.
Refrigerate, covered, until served.

I just made a batch. It was very good. I left out the hot peppers and hot spices because my family doesn't like spicy dishes. It was just as good without them.

I got it from the current Penzeys spices catalog. People send in their recipes using Penzeys spices.
Clare

Pepper Bean Salad
1 15oz. can kidney beans
1 15oz. can garbanzo beans or pinto
1 15oz. can black beans
1 15oz. can corn (or 2 cups fresh or 15oz. frozen bag - thrawed)
1 red onion, chopped
2 garlic cloves, chopped
1 red bell pepper, chopped
1 green or yellow bell pepper, chopped
2 Jalapeno peppers, seeded and chopped

Dressing:
1/2 cup chopped fresh cilantro or 2 Tablespoons dried (or use parsley like I did)
1 Tsp. Ground Cumin
1 Tsp. Aleppo pepper flakes (also known as Halaby pepper)
1 Tsp. Ground Pepper
1 Tsp. Sea Salt
1/4 cup oil (I used Olive oil)
1/2 cup red wine vinegar (I used Balsamic vinegar)
2 limes or lemons, juice of (1/4 - 1/3 cup)

Rinse and drain all the beans and corn. In a large bowl combine all the beans, corn, onion, garlic, peppers. Toss well. Make the dressing, mix thoroughly. Right before serving, pour the dressing over the salad and toss to coat.

I put the dressing on a couple of hours before so it would marinate. Actually it has been more flavorful the second and third day sitting in the dressing.

I saw these suggestions on the Cooking Forum for a cucumber salad. I don't know why you couldn't do the same combinations for a bean salad. Since it is for one serving only, you will have to increase the amounts.

8 oz. Cucumbers (peeled & diced)

Italian
1 tbs. Balsamic vinegar
1 tsp. Olive Oil
1 tsp. Fresh basil, minced
Salt

Asian
1 tbs. rice wine vinegar
½ tsp. Sesame oil
½ tsp. fresh ginger, grated
1 tsp. Lite soy sauce

Indian
1 tbs. plain yogurt
1 tbs. fresh mint, minced
½ tsp. sugar
¼ tsp. curry powder
Salt

Southwest
1 tbs. lime juice
1 tsp. fresh cilantro minced
¼ tsp. ground cumin
1 tsp. V-8 or any tomato juice
Dash of minced garlic

Each makes 1 serving.