I'm terribly sorry, but this is a topic involving Boston. It's a city with nearly 400 years of tradition that stand proudly as a center for culture, the arts, education, science, medicine, and even sports. While you've highlighted this rather well, it is still lacking. Hence, the subject should be "Anime Boston April 22-24, 2011: Let's get this pahty stahted".
Panel is Saturday evening at 7, which means it won't conflict with the Masq as much (if at all) but also means it's likely to run into Bad Anime Bad, which makes me Sad Yuugi Sad.
The line for the masq typically starts Friday, while the masq itself lasts until the 4th of July. Trust me, I talked myself into going to one. BAB usually starts at 9, and the place is packed by 8:30, so yeah. Standing room, anyone?
Also things will probably be a bit better this year in terms of a room. Coming in Friday morning has been stressful in the past, and precious hang-out time is squandered. The Marriott is connected by skybridge to the Prudential mall, making it a lot of fun to traverse the entire mall in costume. If the interest is still there, Thursday would be a great time to go to the Eagle's Den, though I won't be eating any portion of food that wants to leave my body more than I want it in there. The T would make it quick and readily accessible via the green line.