Grammar of "a less nice hangout"
Solution 1:
As a rule, its just easier to say 'worse' - 'less nice' is clunky. Perhaps restructuring the sentence would give it greater flow? For eg. "Neither the __________ nor the _______ worsened the hangout", or "None of these made it a worse hangout".
Additionally, you may want to refine your adjectives - nice can be a bit bland - try something more relevant to the subject - cozy, comfortable, pleasant, etc.