Hello Katherine,
In your first sentence both options are possible. 'Like + verb+ing' is more common in British English, whilst in American English 'like + infinitive (with to)' is more often used.
The second sentence is grammatically correct but does not sound natural in this situation. The active voice would be more suitable.
'Most of the guests had left the hotel'.
Usually when we use the passive we want to change the emphasis of our sentence to the object and what happened to the object, often this is also because the subject (or agent) in your case the hotel guests, are less important or often unknown. In your sentence it seems we would be more interested in what the guests did than what happened to the hotel.
I hope that helps,
Christine