It's probably too late to get the location switched for this event. Part of my job is continuing eduction training logistics. It's very similar to planning/running fan conventions-substitute education sessions for the various events-using the same locations as fan-based conventions.
If you are holding a large event as this one promises to be, you usually have to book the location a year or more in advance (Disgusta's Civic Center is basically booked solid for large event space--where you need multiple breakout rooms--for all of 2008 already!). You usually have to sign a contract with a deposit to hold the space. The amount of that deposit (usually non-refundable) is dependent on the size/type of event.
So, the planners of this convention you mentioned, are probably stuck with the Eastland Hotel for 2008, regardless of how many people complain or boycott the event. And if you boycott the event, you're not punishing the hotel--they get paid regardless--you're punishing the folks who planned/organized the event.
On the other hand, I don't contact that particular hotel when I'm looking for training space in the Portland area. My first choice for large (500-600 person) space with 6 to 7 breakout rooms is the South Portland Sheraton, followed by USM (though not ideal space), and finally the overpriced-lacks parking Holiday Inn by the Bay. For smaller trainings in the 200 person range where I only need 3 or 4 breakout rooms, I turn to the DoubleTree Hotel. If I only need a single room for 100 people, I turn to SMCC in South Portland. If I need a large lecture hall space for several hundred or a single room for less then 70 people, I try to book the Abromson Center or the Glickman Library Seventh Floor space at USM.