So big organisations have regular “offsite” planning days (I know, not just because a large part of my consulting money comes from that source!).
Maybe you think your consultancy is too small to do that. Offsite business planning days – solo style suggests taking a train for a day, and working on the train.
You could also try this at a Cafe, an airport lounge, or my personal favourite, the big tables at the cafeteria in Ikea.