Mine get green beans every day with their kibble. They love them. They also get a few frozen blueberries now and then as a special treat. Mine do like carrots and tomatoes and bits of apples. Little bits of watermelon are just fine. As long as treats, including fruits and veggies are only a small part of their diet your dogs should continue to prosper.
I hear that snow peas are good, carrots, and yams are as well. The only kind of fruit I would really give a dog is slices of apples, blueberries, or mashed bananas. I've seen that watermelon is ok, just be sure to get the seedless kind.
Plain/vanilla yogurts, and cheeses are ok. But you must make sure that your dog is not lactose intolerant.
Chloe eats lots of veggies and fruit. She loves carrots, blueberries, bananas, watermelon, canteloupe. I bought healthy treat bars made by Wellness but I stopped giving it to her since it smelled so bad. I couldnt even open the bag. I just give her veggies and fruit all through the day. Not many calories and she swims alot!