Family of 4 first time to Canada

Hi everyone! We're a family of 4 originally from the UK, currently living in Brisbane and moving back home (UK) so have planned a stop in Canada on the way back as has always been on our Bucket List. We will be visiting in March for my 40th :(. We'll be spending 4 nights in Vancouver and 3 nights in Whistler where I will "celebrate" my 40th. Getting a coach to Whistler.

We'd love some recommendations on:

Must-do activities and sights – Anything we shouldn't miss in Vancouver and Whistler?

Family-friendly places to eat – We have two fussy eaters, so any suggestions for places with kid-friendly options would be great!

General tips for first-timers – Anything we should know about visiting these areas in March (weather, transport, etc.)? We are staying Downtown but more towards Westend side, closest subway Burrard.

Thanks so much in advance! Looking forward to exploring your beautiful city and country.