We just returned from BKK. Stayed at the Pen. We hadn't booked a balcony room but the front desk offered it as an upgrade for $30 more per night. I probably would not opt to do it again. We spent little time on the balcony and since the balcony rooms are set back, your views up and down river are somewhat limited by the rooms on either side. The non-balcony rooms seem to have more window area also. We did love the hotel and thought the breakfasts were outstanding.

I found an online video of the Pen's balcony rooms and they looked a bit long/narrow dark so good to know.
tengohambre -- are you around ?? I'm dubious about the Shangri-La with that room count but perhaps the Krungthep wing feels less vast?
What about the construction? I definitely want to stay on the river this time for part of our stay.