I was at the Palms in November. I had a great experience...but that was partly due to Jaydalee!!!! It is off the beaten path, but I am not a big strip guy as I like more intimate experiences.
So, the one bedroom suite I had had a great tub...In the living room area, and a fireplace. The kitchen was a bit dated, but very functional. True, the balconies are off limits, so if that is your thing, then that would be a deal breaker.
I just got back from some time at the MGM signature. I really liked the rooms, and two full bathrooms were a great thing. Good jacuzzi in one bathroom. A bit of a walk to MGM (walkway) but a hike to the center of the strip.
Cosmo... well, it is getting used HARD. It is THE hot spot on the strip, and it is showing wear in service, and the rooms I have been in are fraying at the edges due to max capacity bookings. It is pricy and you pay for the "hip" factor. I'm not a "hip" guy, so the edgy clubs and pool scene really don't appeal to me.
If I had to choose a great hobby spot I would choose in this order:
1) Palazzo
2) Signature at MGM
3) Venetian
4) Cosmo
Best of luck