I am inviting my sister and her family in April, and she has not offered any money, and I have not asked. She knew upfront when I 1st invited her, I was inviting her to save her the money on a room. She has a family of 8 (her, her dh, 5 kids and her son's girlfriend) so, expecting her to contribute to our meals would not be feasible. So, I am hoping to use her or one of her teenager's as babysitter a couple of times, so DH and I can get out at night alone.
I have invited a friend and her husband and daughter to join us next Thanksgiving. She tried insisting on giving me somethinf for the room, but I told her if she really felt she needed to repay us, she could treat us to a character meal. We would enjoy getting a free meal for a change, and she can feel like she paid something. It is still a considerable savings. So, in the future, I do not expect anything if I am the one who did the inviting, but if they insist on paying something, I will just ask them to treat us to a character meal.