We have this: https://www.amazon.com/gp/product/B00J955FH0/ and have had great luck with it on several trips. My kids are 4 & 6, and they generally want to 'help' setup the tent...having an instant tent makes that WAY easier to deal with. It's heavier and larger than other 8 person tents, but we can have it up and ready (tarp, rainfly, stakes) within 5 minutes. Less time fussing with setup makes us all happier campers.
It is larger than we need, and we're keeping our eyes peeled for tent that fits a 10x10 footprint that'llf it our needs (so probably 6p). As they get older, we'll probably get something that requires more setup/teardown time.
90% of the tents for sale have little to no protection from water ingress. Even if you douse the bitch in waterproofing spray, it still gets in. A real waterproof tent is like $500+.
I have a coleman instant tent that I lay a tarp on top of and tie down with bungee cords. It works ok.