Personally I would go to INSEAD
It's a condensed program, arguably one of the best in the world, phenomenally strong within Europe and recognized by all the major consulting houses both in the US and abroad. Worst case, you take the McK or Bain job in Europe for a year and then transfer to the US. That extra year would just have been time you were at Kellogg anyway. I'll also say that even at the consulting firms I've worked at in the US, I've met several INSEAD people - admittedly the name doesn't have the same cachet here as it does there, but for those "that matter" (eg consulting firms, banks, management recruiters etc) its a name thats known. You might not get the same raised eyebrow if someone overhears you at Starbucks as you would with the Kellogg name, but otherwise, no real difference. The only tangible delta I can imagine is going to be the alumni network. INSEAD is going to be strong, but focused in Europe and Asia I would imagine, while Kellogg is comparatively going to be stronger in the US. Don't know that for a fact, just my instinct.
Also, maybe you can squeeze INSEAD for a little moolah? Get them to get you out of Kellogg with some cashola?
Let me also clarify the Kellogg PT to FT transfer option. It does
not offer this "option", at least, not without a proper application. That is, its not just a question of filling out some paperwork and you transfer over (or else everyone would apply PT and then just switch, the odds are substantially higher PT - like 2x). You have to actually apply to the program and be admitted just like any other candidate. I know several PTers who are trying to make the switch this year.
As for PE - this is such a hard area to break into, I honestly think his odds are slim at either school. I wouldn't let this drive my decision either way.
Btw, congrats to you both, an enviable position indeed.
But one question... what do
you want to do post MBA? Do you want to work in the US?