Only problem with that is at Ballys I was able to get a second room comped for a friend. Can't do that at Mirage
Like PaperPost and others said, would you be OK staying at separate hotels? They're not that far. Could you book the mlife offer for you, and just also book your bally offer for your friend?
They really aren't that far apart location-wise....ask her, she might be more OK than you think with different hotels, especially if it's free for her, PLUS you guys can nosh on extra food freebies with the mlife credit.
OR, my top pick, if you have a suite comped at Mirage, see how much the upgrade to the 2 bedroom would cost. I Don't think it's astronomically more, and you still get all the RC and limo comps at mlife.
I'd either go Mirage for you, Ballys for her, or a two bedoom for both of you at Mirage...you can always use express comps to cover the upgrade. If you're in a suite at Mirage, I'm doubting you have Resort fees, which means that you can apply earned express comps to the upgraded room fee, which again, I don't think will be crazy. Just an idea.
PS if you want to try the two bedroom at Mirage and it shows as "unavailable" online....call. If they're giving you limo service, they might be able to "find" you a two bedroom. I've had hotels book me "unavailable" rooms before on a comp....without my even pushing!