There are good things and bad things about most of the Hiltons in the city (well except for the New York Hilton which I consider to be one of the worst Hiltons in the chain). The DT Metropolitan has some of the smallest rooms in the city, but if you score an upgrade, you can get a great huge room. Same thing with the Waldrof, some of the rooms are so small you can probably touch each wall from your bed, others are huge suites, with a sitting area, dressing room, entryway, etc.
For me, if it's a weekend stay I usually go to the Millenium World Trade. It's not near most things, but there is a subway across the street and another a block away that gets you pretty much anywhere you want to go. I like that because the corner suites diamonds often get as upgrades on weekends are wonderful, and at night it's quiet so you can get some sleep without the street noise if that bothers you.
I'll echo everything said about the Double Tree in Times Square. You are getting a suite no matter what, and again you can score an upgrade to a nice larger room with a dining table, etc.
I don't think any of them would be considered modern, their standard rooms are just that, standard city hotel rooms.