I can see two possible interpretations of your question:
1. Meeting for the 1st time: This is just a straight HELL NO! There are pros who offer FMTY (Fly Me To You) packages, and if they are generally well-reviewed, you can usually rely on getting what you pay for. And you will be paying a lot! But a semi-pro or non-pro SB? You will never see her, or she will try to scam you out of more cash for some, "emergency need that will prevent" her from flying to you - like a car repair, or new luggage, or a kennel for her dog, etc., and then she won't show up. BTW: I know this from real life, Dude. It's all a scam.
2. Flying an already established SB to you for a few days or more. This can be done IF she's proven to be reliable. I've done it more than once when I lived in San Jose, CA and wanted to take an LA-Based SB for a wine tasting weekend in Napa. In those cases, I pay for everything; air, food, hotel, tasting fees and of course, allowance. I typically offer her a "free, fun, all expenses trip" and tell her I'll give her a cash present when I drop her off at the airport. How much? Well if I would normally give her say, $300 for date (with BCD), I'll usually give her some multiple of that based on how many days we were together.
Example: End of trip allowance = Base Allowance X # days X multiple (round out to nearest 100). The multiple gets smaller as the number of days grows. So for a one or two day trip, the math is $300 x 2 x 0.7 to 1.0 = $400-600. For a full week (7 days) the multiple goes down to about 0.3 or $600. For a much longer trip, the multiple is very low, maybe 0.1 or $900-$1,000 for a one month trip.
Alternatively, I have taken a rather practical approach to the negotiations. I have twice now taken SB's on a month-long international trip. In each case, I worked with them to see what expenses they would not be able to cover during the trip (due to time off work or other missed opportunities). I actually made a spreadsheet listing their expenses and looked at amounts, due dates, etc. for each account. Then I offered an amount equal to the "lost income" they would incur from not being in town. So basically, no traditional allowance based on orgasms. Instead I make it so they wont be in more debt when they return, won't be evicted, won't see their car repossessed, etc. BTW: If you are the type of SD that wants to coach her or help her build real life skills in money management/budgeting, this is a good way to actually start to teach her. She's probably never made a budget spreadsheet and may learn a lot about herself from the process.
Now, be aware, GaGa thinks I am an IDIOT for doing this! He may be (and probably is) correct. GaGa will point out that, especially on an international trip (and I mean anywhere outside of the US), there is likely to be an ample supply of fresh, young, sweet local pussy available for the price of a drink plus an "allowance" which is probably 50% to 80% less than you would pay in the States. He is correct. As GaGa puts it, why bring ice to Alaska, or sand to the desert?
But my motivation in both of these trips was to share the experience with an SB that I cared about and who really wanted a "luxury" travel experience with a guy they trusted and liked. Many SB's, despite their profile pics have never flown business or first class internationally, or stayed at a upscale hotel, or gone on a private wine tasting tour, etc. Those pics on a yacht, or in front of a Bently, were taken when a GF invited them for a 2-hour party, or perhaps when a photographer rented the location for a shoot. Sipping from the luxury waters isn't the same as swimming in it.
So to sum up FMTY for trusted SB's:
Pros:
-She will appreciate it and that shows in BCD time.
-You get multiple BCD at a steep discount
-The costs to add one more person to your trip aren't very big, after airfare.
-Can deepen your relationship with your SB
Cons:
-She may still flake. (I had to go solo on a cruise a while back)
-You may find out you like fucking her brains out, but spending another 22 hours of the day with her is boring (or worse)
- You may spend more than your budget if she wants Daddy to take her shopping at some exclusive store. (Negotiate this ahead of time!)
- Can ruin your relationship with your SB.
Good luck with this. Please report back on your decision and let us know how it worked out.
Life is good
The Cat