Do they help? Yes. We enjoy ours, (a 12v model).
Are they worth it? Since the ceiling fan came standard on our coach, I have no idea its cost or what the cost would be to install one.
If you don't have a Fantastic fan, or similar, I would go that route first. However, If it is real "muggy" out, we prefer the ceiling fan.
Tom
2015 Meridian 36M
2006 CR-V toad
3 golden retrievers (Breeze, Jinks, Razz)
1 border collie (Boogie)