We stayed at the Boardwalk in 2001 and the Grand Floridian in 2002. I would stay at the Boardwalk again over the GF. You will enjoy the restaurants on the Boardwalk. Jellyrolls is fun, if you have an adult night available. And I agree, it is great to walk about 5-10 minutes and be at Epcot. After Illuminations, it's great to not fight crowds or transportation, and just saunter back to your resort. Use the boats for MGM. If you have the $$ (and it does take some $$) try Shula's steakhouse across the way at the Dolphin hotel. Also, the Yachtsman steakhouse at the Yachtclub Resort is good. ESPN Club is great for a burger or a quick bite.
They upgraded us to the Garden Suites when we checked in. We just asked if an upgrade was possible, and they gave it to us at no extra charge. At the time, it was about $800 a night regular price. It's worth a try when you check in. Even if they will upgrade you to a concierge room, the breakfast in the Concierge Hospitality room lets you fill up before hitting the parks, and saves you $$ on breakfast.
You will have a great time at the Boardwalk. Enjoy!