exchange $ at Singapore Chinatown it has the best rate there!!! but dont exchange it in bank as that side bank rate is higher than money changer...best are those in pearl center...
maridian hotel is alright it is in the middle of orchARD ROAD OPP TAKASHIMAYA....
u can try going suntec city there are 5 toers there sure for u to walk all day...and marina square just next to it