I am pretty new to mystery shopping, but I would do reimbursement only hotels if it was somewhere I wanted to visit or was a needed stay to hop to the next tier of a loyalty program before the end of the year.
At this point thought, the only hotel shop I have done had a pretty easy report - less than two hours with most of it done in steps during the stay. If i were doing shops that called for much longer and more complicated reports with extensive photo requirements, I may sing a different tune!
I'm sure it also depends on your expectations for mystery shopping income. I'm hoping to make a few hundred dollars a month in supplemental income and enjoy a few perks, including free hotels in places that I would otherwise pay for a hotel. So for me, reimbursement only is acceptable, given my goals and limited experience.