How much would a trip to Seattle be for 3 days?

If I were to go to Seattle for 3 days in April for a convention how much do you think it would be?

For the convention it's about 100 and I'd really only be there for the con and the only time I'd be out is for dinner but how much do you think dinners would be?

Also would transportation be bad? I heard the light rail goes down to the State Convention %26amp; Trade Center from the airport and that's exactly where I need to be.

What about food though?How much would a trip to Seattle be for 3 days?
If you figure $50 a day for food, you should be good. You can get by cheaper, but why not enjoy the nice restaurants in the area? As for transportation, the light rail is cheap and buses cover the downtown area if you don't want to walk.