I just got done with a 4 night stay and to be honest, with all the other options in Vegas I won't be back. Issues:

1. First night went to get a beer at the bar, 4:30 and we were by ourselves at a table with a couple of guys at the bar and the bartender. We waited 10/15 and no service so we went to the bar and asked to order, he said just go back to your table and a server will be there any minute. Another 10/15 went by and no server, with the bartender occasionally looking out way, no server ... We just got up and headed to the strip !!
2. Came back after dinner night 2 at 8:30pm and went to the CL to grab a glass of wine. No attendant (Wed) .. Waited 20 minutes (there was one other person in the lounge) and nobody !! This happens to one of the few Marriott's that DO NOT have an honor (I guess there is no honor in Vegas) so I could just pour myself a glass, it was hidden behind the door. Went back to my room and called the front desk to let them know. The MOD called me 5 minutes later and said he was sorry, she must have been getting food.
3. Ordered room service the last night: Food was cold (burger and fries) and I mean cold.
4. Went for lunch day 3 and low and behold there was a "private party" in the restaurant taking up the whole place. They kindly directed us to the bar where we in addition to a TON of other people wanted to have lunch. Every table full and a couple of dozen people milling around read to pounce on the next open table. We just left, got a taxi and found something.
5. Been here 4 times in the last year, each time asked if there were any upgrades and each time the answer was no.

Its an average Hotel, average service with above average prices.