Majestic Grande (although it's nearer BTS Ploenchit than Nana) would be my usual recommendation in that price range, but for some reason it is WAY more expensive now than usual; at ~5000 baht/night for the random Nov days I checked, you can do much better.
edited: I was misreading the total prices for a multi-night stay as price per night. At the 2500-2800 baht a night (and they do show prices nett, not pre-tax, which is good!) I'm seeing for my dates in October and a totally random pair of dates I picked in November, it's a very good deal and I recommend it.
S15 is directly on Sukhumvit, fairly short walk to Asoke BTS and MRT and slightly longer to Nana, and a pleasant place. I don't think it has a pool, though.
Aloft is a nice property, but quite a long walk up Soi 11.
Last edited by nkedel; Aug 18, 2015 at 11:29 pm