We have eaten at Applebees a few times and found it very nice. Typical American chain restaurant fare, but the service was good and the menu had a lot of choice on it (which is good for a fussy eater like me). However having said that, we haven't actually eaten at one in Orlando - not even sure where you'd find one to be honest. The nearest one we have eaten at was one just outside Busch Gardens in Tampa, which was great because we wanted to eat before heading back up I-4 that evening.
And in answer to your second question, no Sweet Tomatoes is nothing like Ponderosa. Not only that, it's a million times better! Bascially it's an all-you-can-load-on-your-plate freshly prepared salads (which are their main focus), plus unlimited made in-house pastas, breads, soups (and some other dishes as well) for one great price. I'm not kidding when I say we would never have a holiday in Florida without at least one trip to Sweet Tomatoes!