OK chaps, I need some input here . It's off topic, but it is Friday

I'm a consultant and it looks like i'm going to be under some pressure from one client to to travel to the West coast of the US to attend another client's user conference. Normally this wouldn't be too much of an issue, but it clashes with a family holiday to Florida. Obviously I want to see my son's face the first time he meets Mickey Mouse etc and i've also paid for the room at disney - it's not the most expensive one they offer, but it's not far short.

So, the question is, how much money do I ask for to make it worth my while without it seeming like i'm taking the mick/taking advantage of the situation?

Would asking for my ususal (fairly modest) hourly rate to be paid but for the whole duration of the trip (i.e. 80hrs or so), plus first class air travel and expenses be about right?

As I understand it, it's strategically important to my client that they are represented at the conference and it's going to be difficult for them to send someone else. I want to show willing but the trip would have to offer adequate compensation.

Many thanks

PS - to keep it vaguely on topic, I could probably route one way via AA and accrue enough TPs to knock me up to Silver for the year - perhaps this needs to be factored in too....