Personally I found it hard to see many good places in CAT-4.
CAT-5 is much much better. I suggest getting more points and upgrading to CAT-5. Loads of posts upthread about how to upgrade your cert.
Indeed NC5 are nicer! A lot of NC5 used to be OC6 to OC8 which an OC1-5 wouldn't have got you into either. Yes, you could upgrade old certificates in the now defunct former, Marriott only program. We were notified upgrades were not possible after converting into the new program. Although some have successfully skirted around the policy, I think the likelihood of doing so will decrease as time goes by. I redeemed for an OC8 and attached it to the property I wanted prior to 8/18 and have spent a total of zero minutes in contacting Marriott. It has been stress free.

Did I overpay 30K by attaching in the old program? Apparently I did. If I don't get those points back, will I be upset? Not at all. I got what I wanted within the confines of the old program. There were no gurantees I would have gotten what I wanted in the new program or if inventory would still be available for my dates after the hiatus. I call that insurance and well spent too.
Anyone who didn't attach was speculating even if holding off for a Legacy SPG property.
Prior to 8/18 I also redeemed 4 nights, 5th free & paid for a sixth night at the Satiago Marriott Hotel Chile in the beautiful suburb of Los Condes. It was formerally 20K a night and is now a NC4. As a PP I was treated like royalty, friendly efficient staff, nice lounge, I had breakfast daily in the restaurant in lieu of the welcome points which they gave me anyways. I was also upgraded to a Full Suite, corner room, top floor for the six nights. As a non Chilean, you are also exempt from paying the 19% VAT.
Look at this list of NC4 properties and see what is of interest, some of those will be OC5. I don't understand some that aren't interested in NC4 that they were happy to stay at when it was an OC5. I guess 4 is less than 5 so it can't be as good.
My thoughts of course.
James