Everything under the sun is negotiable.
Just be sure to make it clear what you want.
Don't be shy. You aren't likely to ask for something they haven't heard before,
unless you are a huge pervert like me.
Even then, the worst that can happen, is they will smirk and say no.
I agree that if you need to take time, a Prive or escort will be best.
If you are new to Amsterdam, arranging an escort might be more involved than you would like.
The only Prive in Amsterdam that I have any knowledge of is Park118.
It is an old-school bordello, with a Madam at the door and a waiting room.
GIrls get called in, and you are introduced as they pass by.
You can take a few moments to ask a question or two, then you pick, and it is upstairs to a nice big room.
Some with a jacuzzi tub, one decked out as a dungeon.
Smoking a joint while soaking in the tub after the bang is one of my favorite memories!
If you aren't impressed, you can thank the Madam, and just leave.
Prices are generally about 100 for an hour, plus extras if they are offered.
Recent reports from there have been very good.
You can find some pictures and profiles of a few of the girls on kinky.nl
In Dutch, select Vrouwen (women), Nederlands, North Holland (region), and Amsterdam (city)
You will get pages of profiles. If you scroll through, you will find at least three from Park 118.
Each has a dozen or so pics, and a profile of preferences like Pipen Zonder Condom (BBBJ), Zongen Tong (DFK)...
Much more info than is posted on the park 118 site, though it is less than half the staff.
The Dutch site -
http://www.Privevhuis118amsterdam.nl - also has a single pic of about a dozen girls.
Read here, use the search funciton. There are a few reports from Park118 this year.
Go Nuts, and report back here.
Weasel