I may be the exception but I but like Bellagio pool better than Mirage.
Been a couple years since I stayed at Mirage but it was a cluster finding and keeping a lounge chair at the pool.

 

Agreed. If you are all about the pool, it's not like it's a big downgrade from Mirage to Bellagio. In fact, I'd call them equal.

 

I know this isn't one of your options, but Aria pool > Mirage pool by far. Just in case you happen to get a decent offer from them as well.