I had a great 3 day 2 night stay at the signature. You can either enter straight from The Signature entrance or going thru the regular MGM Grand. The Signature is a lot more relaxing and less populated than Grand. Its not hectic which is great on the strip. There's a restaurant and a Starbucks. Other than that, you have to walk to Grand, which had a hosts of restaurants and a food court.
The staff were kind, and the accommodations were very clean. We had a suite that had a kitchenette, 2 beds and a balcony. The bathroom was extreme spacious with a jacuzzi tub, large separate shower, tv, and separate area for the toilet.
The room service menu was pretty expensive which was expected. I'd stay again.