You mention 4-5 star, which is doable, but then you mention near Dhanmondi, not so doable. Also how about giving an upper limit in terms of room price?
Just go stay at the Platinum Suites - Banani Road # 11. More of a serviced apartment vibe. Studio rooms start at $150, free wifi etc etc...plus great location. Restuarants...ice cream joints, not that far from Apollo/United if you happen to get sick
Plus not THAT far from Dhanmondi either.
I'm a big fan of Platinum Suites(never had a bad experience there, and I've spent a total of 15-20 nights there over the years).