I booked novotel soi 4 for my upcoming trip without realizing that it shares the building with ibis. Not sure if check-in reception is shared as well. I should've probably booked my usual mercure soi 11.
According to mercure website, opening December 2016:
http://www.mercure.com/gb/city/hotels-bangkok-v4991.shtml?xtor=SEC-704-goo-[ppc-mer-mar-goo-au-en-th-bro-sear-th-loc]-[mer-v4991-bangkok]-S-[%2Bmercure%20%2Bbangkok]
I've stayed both in landmark and grand swiss. comparing them, is like comparing apple with orange. landmark is much better and luxurious than grand swiss.