Here's a great place to stay in Riga! The flat is as described, very clean and very quite and there is a very convenient possibility to park, which is rarely the case in Riga downtown.
Kārlis even organized a desk in his next-door offices as I had to work "from home" a few hours.
Though we already stayed in many Airbnb in Riga, we now know Kārlis' place is where we'll go next time we get the chance!