I've recently had two, one-night stays at Marriott properties in Istanbul, one at the airport Courtyard and another at the Hotel Asia.
I arrived in the early hours of the morning for the Courtyard stay to a very quiet hotel. The night watchman's command of English wasn't 100% (which is perfectly fine, of course) but he managed to explain that I had a full breakfast as Platinum member. The only Platinum welcome amenity was the points at this hour of the day. The room was perfectly fine; reasonably spacious and comfortable. The hotel offers transportation but there's no information on its website and I didn't get in touch before hand which was silly. The typical airport taxi extortion racket was in full play at IST airport. I was first told it would cost me 300 lira which is about EUR43 (well, back then, at least). I scoffed and walked off. The next in-airport counter wanted 150. Nope. Bugger off. I walked outside and tried to get some cell coverage to no avail. I was approached by a transport pimp (what's the correct term?) and I responded with a great degree of skepticism. I told him where I wanted to go and he asked how much I wanted to pay to which I said 40 lira. He accepted and took me to a driver. I reiterated to the driver, twice, how much I was paying and there was no issue. At the Courtyard, he accepted 40 lira without issue.
The Marriott Asia is a nice property, although unless you want to buy a motor vehicle there's really nothing in the immediate vicinity. The desk clerk came out from behind the desk to hand me my keycard at check-in. The room was large and could be made completely dark which I appreciated. The lounge offering was quite good, well presented and quite extensive. Drinks were available from 5.30pm to 8.30pm although they were still out when I left at 8.45pm. Canapes are served from 5.30pm to 7.30pm. Breakfast was offered in the restaurant as a Platinum and it was quite good, no complaints.