Berlin with daughter and grandchildren

I'm thinking about a multi-generational city break - probably Berlin, as I've been there a couple of times myself. Are there any companies which Gransnetters can recommend for booking flights / accommodation? Normally I would just book flights as cheaply as possible and book an apartment via Airbnb, but with children in the equation, and 6 of us altogether, I don't want to take any risks with either if possible. 3 adults and 3 children - age 12, 7 and 7. Thanks.