How about throw a twist in there - they are asked to come to the hotel all kitted up as you said, and head directly to said floor/door. Upon arriving they will get a call and receive instructions. When they get there the Johnson 'updates' them that they must now kill their way out indiscriminately without survivors if they want to get paid. They are here, they've already come half way, do they say no way, do they shrug and say well might as well. And if they say no, you could make it an elaborate setup by one of your groups enemies, former/current rivals ? Cops are already being dispatched or maybe even starting to arrive as they get that call.
This would preset a different type of character internal quarrel - do you finish the job you agreed to do, or not ? My Combat Medic I play has 2 major rules about runs, he is a man of his word, thus will give it his all to complete a run he takes, and he does not slaughter/kill innocents or unarmed. Honestly I think he would break this contract because it wasn't what he thought he was agreeing to in the beginning.