This is rather long winded but....
While I absolutely LOVE this idea (wish my hubby would do this for me!!) I think there may be a few logistical things you haven't considered.
I'm not exactly sure from your post as to your schedule for Monday but I am assuming you are flying from Miami presumably early afternoon since you said you would get there around 6.
So were you planning on your wife going to work in the morning and then picking her up in the limo? If so, I don't know what she wears to work but personally I wouldn't want to go on vacation wearing "work clothes".
If you are leaving before she would normally go to work, were you going to tell her as the limo arrives? Will it stress her out having no time to prepare to leave the house?
As footballfans mentioned, she will probably want to say a "proper" goodbye to the kids. Will they be around when you leave the house?
Also, there might be plans for next week with regards to the kids, etc (appointments, school functions, projects, etc) which you may not be aware of that she will want to have a chance to arrange for someone else to deal with before going.
Anyway, my point of all this is that I would tell her sometime Sunday morning. This gives her some time to prepare but still is a HUGE surprise. For me, finding out that I am leaving in 24 hours and everything (or you think everything ) is arranged for would be FABULOUS!!
I think Randymon's suggestion of him telling her is a great idea. Or perhaps go out in the morning and buy her some flowers and tell her on the card. Maybe make her breakfast in bed and you and the kids can tell her! I think making the "telling her" something special and then her having a bit of time to prepare can only add to the whole trip.
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