Stays within the last week:
- Marriott Heidelberg
- Renaissance Hamburg
- Renaissance Penta Vienna
- Renaissance Vienna
Experiences:
1.) Amenity choice card offered automatically during check-in.
2.) Breakfast offered automatically (Heidelberg, Penta Vienna: Lounge; Hamburg, Ren Vienna: full buffet breakfast in the restaurant).
3.) Upgrade to a much better room at all properties (Penta Vienna: Business suite; other properties: larger/corner room). All rooms were definitely better than booked. (Often (in the past) the check-in agent mentioned an upgrade to deluxe or executive room - but it was unclear what the difference to a standard room is. During all 4 stays, the upgrade to a better room was obvious).
4.) Welcome letter (Heidelberg: standard letter explaining the lounge benefits; Ren Vienna: personal welcome letter).
5.) Better/more bathroom amenities (Heidelberg, Penta Vienna, Hamburg) + complimentary bottle of water (Heidelberg, Hamburg).
Overall:

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BTW, the Renaissance properties seam to get new bathroom amenities labelled "re" (soaps, lotion, shampoo, shower gel, comb, ...) !? (The liquid now pours out of the small bottles compared to the former semifluid bulk.)
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Pictures from hotel stays
Basic Hotel stays/nights/points calculator
Short overview: KLM FD, LH M&M