Hotel In Siam Area with a good gym

I am heading to Bangkok for a few days in the Siam BTS Area

I am looking for a hotel with a nice gym, that has some cardio, some machines and some half decent free weights

its hard to tell from hotel webpages as they often use that fake gym photo then you go there and you find a little tiny gym or something

I would also be interested in a gym in the Siam area that was not part of the hotel that I could go in and do a daily drop in rate

I am not looking to break the bank on the hotel 75 to 125 bucks a night i would guess

any suggestions on hotels or gyms in the area ?

thanks