This sort of thing is always difficult.

Are you going to be in 'escort' mode 24/7 or will you get/do you want time on your own? Is he a demanding sort of chap or very easy going? Will it be a lot of fun or a lot of hard work? Is he loaded or is this pushing his financial limits (not your concern theoretically but its a factor for some). There is a lot to consider.

Some girls would charge the overnight rate for each night (so ?1600 in total) so as to compensate for the fact that it is all expenses paid, others will double it to come up with a 24 hour rate (so ?3200) and some will opt for something in the middle. Some will even go for just the one overnight rate plus expenses paid.

There is no right or wrong answer, just make sure it is something you are happy with.

I see a guy every 3 weeks for 3 hours, always pays the full rate and still does.  I did go away with him for 3 nights and charged him for 1 because he is a) a good customer and b) a brilliant laugh.  I knew i wouldn't have to do much 'work' and had a fantastic weekend away abroad without any money worries.  I wouldnt go away with anyone I hadn't seen a few times and would have to get on with that person and 'trust' them, at the end of the day your going to have alot of personal items with you and you can't be worrying that the guy is going to scam/steal from you. 

I could have made more staying at home but I was treating it as a holiday for myself as well.