
If she is used to being in the centre of the family and you will not be having strangers disturbing her in the kitchen (as of course you would need to be close to her at al times in the early days) then the easier to keep warm kitchen would be my choice.
When my children were small I used my bedroom, and was up and down like a yo yo, as of course the bitch was torn between her maternal instincts and wanted my company, and I had to supervise.
Once my two were grown up the whelping box has been in the living room, and moved to the kitchen at 2 - 3 weeks (depending on how protective the bitch was re her fellows), where the other dogs spend most of their time, as I could have a larger pen there than in living room