So what I did myself - White Sands office offered converting to J$, so I'd go and get anywhere from 60-100 each day whatever I think I'd need. Their rate was a lot more competitive in Nov than April. I think in Nov it was only $2j off the cambio rate my driver told me. This time it was more like $6j off the cambio rate. But I'd a matter of paying for convenience too. I was fine with it, your mileage may vary, you may like it or not, or your hotel may not offer it. Worth asking IMO.
~Moose