A overnighter is anywhere between 1500 - 2500+ (with sex)
I would imagine a overnighter with sensual massage would be around the same but you maybe able to get it for slightly less. It's really up to the WG to prescribe a rate for the time spent with you. Unfortunately, I don't have a WG that does a similar service with sensual massage but I am sure if no further suggestions, you could just ask a WG that you fancy on NZG to give a quote.
Also keep in mind that an overnighter with someone you don't click with can be painful for the both of you!
my 2c