The first thing to check out is service from the fire alarm installer. Make sure the people installing the system are the ones who service the fire alarm system.
Also, make sure that they install the wiring, and not just subcontract out the wiring to someone else who will never be on site again. Your fire alarm system is going to be in the hotel for years to come, the people who install it should be the ones taking care of it.
Talk to a few other maintenance people for hotels of your size. The maintenance people will be able to tell you about service from fire alarm companies.
The brand is important. All brands are proprietary to the manufacturer, but some will allow you to change service companies should there be a problem with the service in the coming years. Make sure there are several companies that can service the system, and the panel.
Again, talk to maintenance people, they can give you insight regarding which brand is best.