As I recall you have to go up a winding circular hill to get to the door. As you may know, many Asian Hilton's are set up this way to discourage any passing rif raff and encourage limo access!
The Hilton is a somewhat better hotel than the Landmark, which I think is east on/near Sukumvit close to the Convention Center. i prefer this location and stayed down the road at the JW Marriott last year.
Stimpy makes a good point, especially regarding tuk tuks which I never take! You can get a cab at the door or walk dwon to the street at the Hilton which I remember is on Wireless Road.
Adding to the suggestions for fine Bangkok propertirs, The Sukothai, Regent, and Oriental get my votes for the top three here and surely each is also in my top ten city hotels worldwide.