A lot of guys go at the travel opportunities in completely the wrong way and then wonder why they get shot down, and even rejected as a regular client. They position it as an offer, rather than an invitation. Fact is, almost every SP working at $250+/hr can afford to pay her own way to any global destination of her own choosing, anytime she wants, as often as she wants. Most neither need, or wants someone to 'pay for her' as if it was solving some unattainable goal of hers, or some glammed up charity donation. You're not offering her anything she can't secure for herself independent of you.
Most SPs will see it rather as a mutually beneficial business transaction, where she gets paid as usual to accompany the client to a destination of HIS choice, and provide typical 'companion' services. If she likes the client, it's an added bonus for her, but its a bonus, not the core reason why she's going, no matter what the client may believe. She may give a 'volume discount' or fixed price for her time, but that doesn't usually indicate anything more intimate than her having a good business head on her shoulders. But in her mind, it's virtually always a business transaction that happens to have some attractive fringe benefits.
Best way to approach it is by inviting her to join you on a trip. If she accepts the invitation, as Miss Croft says, it's because she feels it's because your personal connection is positive enough that won't impinge on the business transaction to come. Negotiating an appropriate fee for the travel/companion services is much easier to get through after that.
Guys still need to remember she's there 98% for the business transaction, not because of a strong personal/intimate connection they imagine exists in some form as a motivator. She'll never confuse love and business, but soooo many guys do it's ridiculous.