I have a booking for this weekend at Danube Waterfront and I got informed that we can have breakfast between 07:00 - 10:00 AM and the Room Service is available between 06:00 - 10:00 PM without tray charge and that's all, everything else is closed. Now I'm curious if the Room Service is available from 06:00 AM or PM... Anyway, last night my wife looked on Plaza's page and they have the Lounge open but with reduce service. I thought that it's a mistake but they confirmed it so here it is: "As the Executive Lounge operates currently in a limited version in our Lobby area, you can enjoy coffee, water, soft drinks and snacks during the day. As well as the upgraded breakfast from 07.00 – 10.00 AM in our EMILE Restaurant.". I'm tempted to change my reservation to Plaza for this weekend but, if not, the other weekend I'll definitely be there and I'll give an update.
One other thing, starting today there's a new promotion (at least for the Vienna's Hiltons, didn't check for others).
Here are a few examples:
For Danube Waterfront: 1 or 2 nights in December got from 92 to 81 EUR/night and in January from 84 to 74. For 3 nights or more the price got from 84 to 74 in December and from 78 to 69 in January. For a general idea, the best price this year was 73 EUR/night after the lock down but it disappeared fast.
The other 2 Hiltons have also better than usual good prices, you should check them out.
And regarding the local restrictions, take away is available.