Me and my partner stayed 3 weeks at Janis's place, we worked some of the time as well. The flat is very well suited for longer stays, and can accomodate 2 people working no probs. There is ample space - my partner used the bigger table in the living room, while I used the small desk in the bedroom. We still had a dining table in the kitchen - which is very convenient since you don't have to move anything just to have lunch. The internet is easily fast enough and reliable for any reasonable uses.
The flat has clearly been designed to be lived in rather than rented out, so there is plenty of storage space, and all the little bits which you might need (umbrellas, a yoga mat, extra duvet). The living room is also spacious enough to do your yoga/excercises in front of the big TV. The space was super clean and very comfy.
I normally don't like staying in the same place twice, but if I need to come to Latvia for more than a week Janis's place will definately be my first call.