from LV to Yellowstone and back

[hanula]

Hello,

first of all I want to thank you for your advices for our trip we had earlier this year, it was awesome, also thanks to all these tips! Thank you again, I really appreciate it. Here is the planning thread.
I´m here back again with planning of our next trip to US as the country has dazzled us.
Next year we would like to visit Yellowstone, probably in September ( maybe late May, not sure yet ).
We would spend about 5 days here.
We want to fly from Europe to LV, here rent a car and go to Yellowstone and back.
In Vegas would spend about 3 days and then fly to NY for about 5 days and back home.

As we were on a roadtrip this year, we have already visited some places ( LA, GC, Mon.Valley, Arches, Bryce, Zion, Death Valley, Yosemite and SF ) so our biggest wish is to see something new..That´s why Yellowstone and NY.
Las Vegas because we really liked it during our visit.

My question is if this plan is doable. How it is with the flights within US? I found some tickets from LV to NY for about 200USD..

Or do you have any idea how to plan the trip better? Which places to add? Our planning is at the very beginning so we can
make changes..

thank you!