A $1,000/night bankroll for 3 nights is probably not host-worthy at MGM these days.

I think you probably should be able to get enough play out of your bankroll to get rooms at all of their properties without resort fees. MGM doesn’t require Gold status to get out of resort fees (yet). If your play level is high enough, they waive the resort fee for comped nights. You might get shut out at the higher end properties (Aria, Bellagio, Cosmo) on some weekend (or other unusually expensive) nights.

You probably won’t be able to get extra rooms from MGM without a host involved, except at the regular 15% member discount.

CET will give you more room nights (up to 7 comped). MGM will give you fewer room nights (usually 4 night max comped, then a good discount for additional nights). MGM partially makes up for that with higher freeplay and resort credit (at least in my case). And the discount for extra nights beyond the max fully comped is usually very good (up to 80%).

If your trips are normally only 3 – 4 nights, it’s worth thinking about. Needing extra rooms at a good discount may be a hitch without a host.

You don’t necessarily have to commit completely to one or the other. You could stay at CET, take one day’s bankroll (or half of that) over to an MGM joint and play it and see what you get for offers, I’m sure you’ll get some comped nights even on a $500 bankroll. That gets your foot in the door at MGM without having to pay for a full stay.

Then you’ll have offers from both in your pocket. You can try a full comped stay at MGM, see what you get for offers following that, and take it from there.