I used Sami World Travels on a recent trip around the Golden Triangle. Drove each of the three legs (Delhi-Agra-Jaipur-Delhi). The longest stretch was Jaipur to Delhi, which took about 4h15m. If you can get a van I think that would be better than flying between any of those places. The extra hassle of arriving early etc. outweighs concerns about the length of the drive. The one issue could be finding clean toilets along the route. Wasn't an issue for me but I imagine it could be for others.

I wrote a review on TripAdvisor. From what I saw of the other reviews there for Sami, they seem plausible.