Thailand or Vietnam at Easter?

[SparePantsAndLego]

We’ve been to Thailand with our son twice since he was seven. We’ve also been a fair few times on our own. We love it BUT we’re now tied to school holidays and can’t go over Christmas, so Easter is the only time that works.
This means we can’t do Chiang Mai and other places we’d love to take him, as it’s not a great time to visit.
I’m now wondering if we should try Vietnam. It’s somehwere I never got round to visiting pre DC.
We like independent travel and won’t do all inclusive, I love warm seas but realise we do need something more than a lovely beach for few weeks. We typically round off the trip with a few days in the city, so we’re not averse to a bit of hustle and bustle...
Any thoughts or recommendations? Which would you choose?

I love Vietnam. Hoi an is lovely and weather is dry then and not too hot. Hanoi is great for museums, wandering around the old town, fabulous restaurants and day trip to tam coc (like Halong bay, but inland!). HCMC has great museums too, day trip to cu chi tunnels and if you want a few days to relax the Mekong delta is lovely.
Sapa is great for trekking - but not sure about the weather in April. Hue is also very interesting and only 3 hours or so from Hoi An.
Internal flights with Viet Jet are good value and I have also done the overnight train from Hanoi to Sapa - there is now a bus, but the overnight train was fun, but very slow!

Forgot - I also recommend vespa adventures - brilliant fun. We did this with dd in HCMC and Hue and she loved it too. She was about 10/11 the first time so suitable for children.

This is brilliant and really, really helpful. We did an overnight train to Chiang Mai and we’d love to do that with DS, so a slow overnight train sounds great.
Thank you again for taking the time. I’ll get Googling today!

How much was your flights and where did you book?