I feed my rabbits a wide range of veggies for variety. I know I certainly wouldn't want to eat the same food every day of my life :shock: and I'm sure they don't either. As long as you do it properly, there should be no issues with upset tummies.
I feed 3-4 of the following each day, Spring Greens, Romaine, Rocket, Spinach, Celery, Kale, Savory Cabbage, Peppers, Parsley, etc, pretty much everything they can have, except broccoli or cauliflower as they don't like it.
(don't blame them, :lol: I don't eat veg at all.)
They also get some fruit every few days, apple, banana, kiwi, cucumber, carrot (not fruit, I know), Maddie shared a yummy peach with me today.
My bunnies deffo eat a lot better than me. :lol: