Actually just had a rethink on this and casting my mind back to dozens of car and taxi journeys in and around Bangkok over the last 20 years.... if you're having to travel to a particular place several times my advice would be stay as close to that place as possible

Whilst the Hyatt may be run of the mill by Bangkok standards that shouldn't necessarily put you off. In virtually any other city in the world it would be one of the best - it's a solid 5 star hotel, with a lovely lobby area - a bit like a tropical version of the Peninsula in Hong Kong's lobby (FS Lobby next door is not dissimilar, but that used to be The Peninsula Bangkok when it first opened many moons ago). As others have said, there are several hotels that are adjacent or a few 100 yards away that are excellent if the Hyatt really isn't suitable. Whilst I like the river I think if your having to make the journey several times a day it will quickly become tiresome.

Bangkok is a sprawling city and traffic is terrible virtually any time of day. Don't rely on taxi's - they have a terrible reputation - when they're not trying to persuade you that the place you want to go to is closed and trying to instead take you to a "sauna", they're telling you the meter is broken, or half way through the journey trying to renegotiate the rate ("oh you meant Grand Hyatt Erawan Hotel, I thought you meant Grand Hoput Bezawan (or some other made up place) that 'll be an extra 500 baht"). More than once I've abandoned my journey with a Bangkok Taxi.

Most of the worse taxi journeys I've taken have been in Bangkok - we once had a driver who we were convinced was probably, by any reasonable definition, blind. His glasses were thicker than my old grandmother's (who was registered blind). One of his eyes was opaque and he seemed to be constantly put eye drops into both of his eyes whilst driving.