When we traveled in the UK last year, I loved the times we had apartments - cook our own food, have everyone together, have some space to spread out. We much prefer renting condos or houses over hotels, but it is really up to you what you prefer. Is it more important to be right there at the convention center or is it more important to have some down time? Do you mind cooking?
I'm not a good one to ask about traffic because DC has ruined my perception of "good" traffic. Is it as bad as 495 at rush hour? I don't know.
For me, personally, money would be a big factor. Not only is $1600 a lot of money, you're also paying for food (unless it's a suite you may not have the ability to keep food in the room). With a townhouse, you can stock up and eat at home more nights (or more mornings - what kind of breakfast does the hotel offer?). How much would you leave the convention center? Does the center offer any parking specials? Can you buy a pass for the week?
You need to make a list and figure out what you want out of this trip and what is most important.