Ditto pps - DS is 10 months and really likes people watching and seeing new things, regardless of where they are or if we'd consider it "fun" or "kid friendly". He loves to be outside, even if it's cold - he actually giggles and gets excited when he feels the wind in his face and hair.
From someone who's been travelling with LO a lot lately, I'd say to defer to the parents on what they'd like to do and don't worry so much about planning outings. With DS sometimes it's a lot easier and more enjoyable to stay at the house of the people we're visiting and just let DS play with his toys and take his regular naps while we enjoy the time with our friends/family. To him, the new house is a new and interesting place anyway!