I'd definitely recommend NYC over Cali, no shortage of things to do/see.
If you're open to Central America, I can't recommend Costa Rica enough.
Eh, NYC is definitely not the place to vacation for 1-3 months. It's a concrete jungle that gets boring really fast and NY state itself is just...boring. And if someone wanted to explore the Northeastern US there's much better places to stay longer term. Cali at least has Napa Valley, San Diego, San Francisco, and LA.
Just to focus on the US: NY is great for a few days, maybe a week. Cali is great over 1-3 months, great mix of urban/rural stuff. New England is great over that time frame too, especially if you stay in Massachusetts where pretty much everything nice is accessible with a short drive or train. Go see Shenandoah (this ain't in the NE US but it's worth deviating) and go to Yosemite. Mount Washington and the White Mountains are cute too. Cali is great year round, northeast US sucks if it's not a warm spring or if it's not summer.
I spent a month in Japan though and that shit was lit. Airfare was expensive, but I also flew first class. Alcohol is cheap as fuck. The food is lit and there is soooooooooo much to take in. No weed tho.
Canada is basically just the state of Vermont with legal weed and some angry frenchies.