We do a lot of small weddings where there’s a similar scenario – they want something small but which can also work well if they want to dance.
I might recommend the trio. We sometimes perform at Oblix at The Shard and it’s the same here. They like us to start chilled and midbeat, but then have the option to go upbeat when they’d like us to. As it’s a bar not everyone wants to dance, but we do usually end up with a mini impromptu dance party in front of us 🙂