Hmmm, some clients do expect a free holiday. I'm always firm, but I do hate being looked at as if I'm being unreasonable.
One man kept asking, not expecting to pay, I did go on one holiday with him free because it was to a place I'd been really interested in going to, and just wouldn't have gone otherwise. I laid down rules and boundaries, also that I'd get a certain amount of me time. I also knew from his bookings that he wasn't going to be shagging non-stop. He covered all my expenses, I did however take my own emergency cash and cards.
Later on after asking about further time away, he did realise I'd need to be paid, and invited me to a wedding which involved an overnight stay. This time he said he would pay whatever my rate would be. I agreed a fee which was a bit less than my standard overnight, partly because much of it was public socialising, but still a fair whack representing two days work. Worked out well. He moved on when he found out I was getting married my own self!
What I'm trying to say is if you stand your ground, it does eventually sink in and if someone wants to spend time away with you, they may well stump up.