I have chosen the Hotel Sevigne for my 11 nights (alone) in Paris in June (sooooo excited). The difference between a single room and a double room is €14 and single/double bed. Is it worth the € to take the double? When I was in Venice, I found the single room to be quite small and the bed quite narrow. OTOH, €154 extra..... (amenities are the same)
If it were me, I'd take the single. How much time do you plan to spend in your room, anyway? When I travel I'm only in my room long enough to sleep and get ready for the next day. And chances are, if a single isn't available when you arrive, you could get put in a double anyway.
From my experience, even double rooms in Paris can be quite tiny. I doubt 14 euro will buy that much more room anyway.
Really I was more worried about the width of the bed - in Italy the single beds were NARROW, which I found to be uncomfortable. The hotel just wrote me that the single bed is quite wide - well over a meter, so I am taking the single. Thanks for taking the time to write.