I've stayed at the Imperial Riding School Renaissance about 3 weeks ago. My wife and I spent 3 nights there. We got a pretty good advance purchase rate (€116/night).

- This property is formaly known as PENTA; they're one and the same.
- As a Plat, I was upgraded to a business suite (on the 6th floor), which was nice. ^ (I even selected a 1/2 bottle of wine for the plat arrival gift and they sent a whole bottle to my room.^ On the other hand, "mixed nuts" were just a bowl of salty peanuts. They may have mixed them in that bowl, but there wasn't an assortment per se. Maybe a language thing... )
- We also got lounge access, but that was expected.
- The Imperial Club is actually the lounge (fancy name, I suppose). It's a separate building from the actual hotel, directly across the driveway. It's probably the best looking lounge I have seen at a Marriott, VERY nicely decorated. ^ It's pretty big but has surprisingly little actual sitting space. We've never had a problem finding seats, but with just a few people there it felt almost full. The food was good, and we really liked the wine offerings. One odd thing: they also have some cocktails for sale. One of them was a screwdriver for €8 (~$12); yet there is vodka and OJ available so you can make it yourself for free.
- 10 minute walk to Stadpark, another 2-3 minutes to the Ring. It's a 12-15 minute walk to Wien Mitte S-Bahn/CAT station. I definitely recommend the S-Bahn. Overall, very decently located! There is a Billa grocery store 2 minutes away from the hotel and there are some restaurants on that street... I think it's called Ungargasse.
- I found the staff very polite. They weren't exactly friendly, but I got the feeling that they were eager to help. Very professional! I found the cleaning a bit incosistent - sometimes they'd wash the wine glasses, sometimes they wouldn't, but overall pretty good.
- The negative: I never got any kind of receipt. They never slipped one under the door or placed one on the door knob. I haven't asked for one from the front desk as I checed out (because I'm just not used to it.) An e-folio was never emailed to me. I wrote MR and got a canned answer, but after I replied to that email MR contacted the hotel on my behalf and then the stay posted to my account.

I would recommend this property. My wife and I liked it.