We did it one night, it was quite enjoyable as it was a nice leasurely trip. I hear during frieworks the driver knows some cool places to watch them form, but don't know by experience. I think they still do it though, and to me it was fun.
We did a carriage ride at Port Orleans. As I recall, it was $35 for 30 minutes. We chose PO over FW because the reservation representative asked if we preferred riding through the French Quarter walkways or through FW (more of a wooded area). Only downside to our ride was that it was raining... Also, they sell out, so reservations are a plus.