I would check out Sugar Babes International, as well as Discreet Elite, and Aprov. In the UK at least, Adultwork is very popular. Eurogirls Escort comes highly recommended, and has the largest directory of searchable active escorts in the world. I recommend it with some reservations, as YMMY. 

I’ve personally had amazing experiences with Eurogirls escort; was recently able to secure a three-week long booking at the Four Seasons in the Maldives with a stunning brunette Russian provider, for a very reasonable per night gratuity; it includes BBFS/A-level & unlimited MSOG. Total cost for the gratuity was only $26k, very reasonable, not including accommodations/meals and airfare. To say that it is the stuff of fantasies is an understatement. I will say that luck played a part too, as finding the right one is key. 

I’ve also seen many PSE providers on Eurogirls, including many that aren’t available stateside. I highly recommend checking it out and seeing what options are available. You might just find a goldmine like I did. A quick search and query shows that Sofi Goldfinger offers weekends for $20k plus flights and accommodations for a true PSE with absolutely no restrictions, and everything included.