In my experience, the Renaissance never upgrades anyone, not even this longstanding PP, from Barlow to Chambers rooms without an extra charge, usually in the neighborhood of �100 per night, though the offer has been known to vary. I do not know if SNAs will change this longstanding policy, but given the tenacity with which the Renaissance has clung to it, I would not expect an upgrade from Barlow to Chambers. I have received upgrades WITHIN the Barlow wing, but the difference between the various Barlow rooms is negligible. If, however, you book a Chambers room, there appears to be a decent chance of an upgrade to a better Chambers room.

As to rollaways, none of the Barlow rooms allow a rollaway bed. Chambers rooms do. As an FYI, this information is available on the Marriott website. When booking you simply click the "room details" link to the upper right of the room type you are viewing. Availability of rollaways is listed under "Beds and Bedding."

As far as lounge access is concerned, you currently have access to the Chambers Club due to your Platinum status (by linking your accounts), but it is unclear if this will continue in the new program. You may want to call or write the hotel and ask. This hotel does NOT consider the Chambers Club to be a concierge lounge. They call it a private club. Currently MR Golds are treated as if there is no lounge and are given breakfast in the restaurant. It is entirely possible that this becomes the policy for Platinums going forward, and possibly for PPs. We simply do not know.

Finally, regarding under-12s, please note that the Chambers Club does not allow access to guests under 12 years of age. I am not certain how strictly this is enforced.

Not 100% true. I was upgraded on a one-night award stay from Barlow to Chambers in December 2017 with no fee without even asking. (I was and am Platinum.)

That being said WRT to the OP, I believe award stays are more likely to get upgraded at all the major chains, but 5 nights is pushing it.

I prefer Park Lane even as Platinum. Found the Barlow Wing rooms (normal rooms) very average.

Just stayed here for 5 nights. This was my 6th stay at the St Pancras in the last two years (5 business, 1 family). I usually stay in the Barlow wing but this time I was booked into a Chambers junior suite (166) facing Euston Rd. I've also stayed in the Grand Junior Suite across the hall (167) on a prior trip with the family.

In general I really like the St Pancras. It's got a great location for business and the Chambers Club is great. However two aspects of this particular junior suite made the Chambers wing not worth it. First, there was A LOT of road noise from Euston road at all hours. They provide complementary ear plugs (always a bad sign) but even with the plugs there is a lot of noise. The windows are huge so I guess some noise is to be expected, but the hotel should really invest in a second layer of sound proofing windows. Second, the "king bed" was two singles attached together and it was very uncomfortable. In contrast, the Grand Junior Suite (167) I stayed in was very quiet (despite having windows that directly overlooked the restaurant and the train station) and the bed was a true king bed.

Net, net: my suggestion to anyone staying in the Chambers wing is it make sure to request A) a room facing the station/interior B) a room with a true king bed (if that's what you want). Personally I would opt to stay in the Barlow wing if they can't make that guarantee as at least those beds are all true kings/queens and there is almost no road noise.

I should also note I could swear that there was a recent post from, I think [MENTION=680784]bhrubin[/MENTION], where they actually checked out of their Chambers room because they couldn't stand the road noise and the bed but I can't find it anymore. I remember the post because when I read it I said to myself "that's not my experience" (from room 167), but after my experience in 166 I totally get where they were coming from.

Thanks for the tips. Much appreciated.

Cheers.

The terminal noise from my non-road-facing Chambers room in December was pretty bad. But, I was only there for one night. It sounds like if you want quiet, the Barlow wing is better.

We (two couples) stayed at St. Pancras for two nights last week. We chose it for availability with Marriott points and for the ease of arrival by train from Gatwick airport. Group fare from Gatwick was 28.50 pounds and was very smooth. Upon arrival, we were offered a suite in the Chambers wing for a couple hundred additional pounds. The suite was large and lovely but more than we needed, so we kept the rooms in the Barlow wing. Our room was fine, but quite ordinary. As Gold, we enjoyed complimentary breakfasts and evening snacks (enough for a light dinner) in the Booking Office, which saved both time and money. The staff was helpful and friendly. Although the concierge desk did not recommend Uber (I suppose they have some arrangement with the cabs?), we used Uber a couple of times from the hotel and were very pleased with the result. I would book there again, but would also consider other recommended London Marriotts on future visits to London.

I had a great 5-night stay here using points! The hotel was very busy. They can only offer an upgrade to the Grand Jr Suite on the first night, which I gladly took, although I had to move rooms later. Regardless, access to chambers lounge was provided to plat elites which served buffet for breakfast, afternoon tea and evening snack everyday. Breakfast was also served at the main restaurant - Booking Room. I had to vacate the suite and move to a room in the Barlow wing. It's a regular room with views of the adjacent British Library. I got king beds in both occasions which were basically two single beds pushed together. You can't really feel the gap in between, but I thought I should point it out. The second room was small but immaculately kept clean, in fact I felt the small room was cleaner than the suite. I had terrible allergies on the first night which was caused by dust. I knew it came from the carpet and the 20-foot curtains in the suite, because when I moved my allergies stopped. My only issue with the smaller room was the bathroom. There was no bathtub, the exhaust didn't work so it always stayed humid after every shower and the toilet flush located immediately behind the toilet seat. Other than that everything was great! Perhaps the best thing about the hotel was the location, it's right on top of the train tracks. I didn't hear any noise, at least from the rooms I stayed at on the second floor. Tip: There's a shortcut to the tube, take the exit from the Booking Office to the train station, walk past the Mi+Me, take the set of stairs and follow the sign. Also, if you get access to the Chambers Lounge, get your self acquainted right away with the staff - they're the stars of this property.

In the end we stayed at the JW Marriott instead, same number of points. In June this was 180k for 5 nights, with 1 night free - Only 60k SPG points, what a deal. We were upgraded to a large corner room, kid bed no extra charge, lounge and great location. Could not have been better. Really glad I did not gamble with the St. Pancras.

I can confirm that it is only PP that get access to the lounge (unless staying in a Chambers Club room) and regular P's do get breakfast in the restaurant (stayed a couple of weeks ago). As for upgrades from Barlow to Chambers I doubt that is likely but not such a big deal since if you are PP you get lounge access anyway.

I got an upgrade three weeks ago, but only for a one night stay, and I had to leave early...