Just been through and did the two "other" options
1. The "rest" lounge on the first floor of the al mourjan lounge is FCFS and it can be hectic. 1. the majority of showers are there so in/out of people. you can only book them for 6 hours. Actually you can't book you have to be there early when someone leaves. One guy recently said he paid for the lounge because he thought that he was guaranteed a rest spot. there are small private cubes to the right of check in, but they are also open air with curved beds. Somewhat quiet. I was told there was change over for two spaces (out of 8 I think) was 11pm. I showed up 20 minutes early at got one. Others showed at 11pm and didn't . Was private, and somewhat restful but not perfect. Not gauranteed, be prepared to get there early.

2. I also did sleep and fly for 10 hours on a 14 hour layover (had access to al mourjian for a shower). There are private, semi quiet, small with a double bed with only one side exit access and not much room for luggage. Air con was good. We checked in at 10pm and was woken by the 11pm and 12pm change over, but then quiet until then. You pay by the hour and 10 hours cost me $260

the oryx was booked and would have done that if open.