Lisa, there are quite a few rides at Epcot:
Soarin
Living with the Land
also for $12 you can tour the greenhouses...they give kids ladybugs to release at the end
Spaceship Earth
Test Track
Mission Space (with a "new" version)
boat ride in Mexico
boat ride in Norway MAELSTROM!
I bet they would really enjoy coloring the mask in each country....there are tables set up with loads of markers and the CM's add a stamp to the wooden handle, a token of their country and the kids sit and color it. If they get stamps from all the countries they get a special poster at the end. The mask changes throughout the year....some will have the Flower and Garden emblems, some Food and Wine Fest...I can't tell you how many of these suckers we have....and yet, I don't think we have but one fully completed....

Future World has a different version of the mask, sort of a lanyard backstage pass looking deal, but very cute!
Characters, we probably have seen the most characters at Epcot.....the "usual" is the fab five at the character connection, Brother Bear - Koda and someone else...not sure of their names, but got their autograph, in Canada. Alice, Mary Poppins, Pooh, Tigger and Eeyore in the UK, Belle, Beast, and Aurora in France, Aladdin, Genie, Jasmine in Morocco, Pinochio and Geppeto (butchered both those) in Italy, Snow White and dwarves in Germany, Mulan and Mushu in China, outside SE you'll find Mickey and Goofy decked out in astro gear, etc.....
and of all the parks this is where we've had the best interaction. We sat at the mask table with Alice alone and she colored a mask for Samantha, for a good 20 minutes over the 4th of July weekend. I think people mainly do not come to Epcot thinking characters so they aren't looking for them or aware they are there. In UK, France, China you would pass them by and not know they are out...the rest are out front where you can kind of see.
The Santas around the World are nice, the tree lighting each night is fun and the candlelight processional is awesome. We did the dinner package as I hate standing around waiting for stuff. Epcot has a lot to offer! For me....mainly it's much slower than MK and since the countries are more spread it really never seems that crowded to me. During the Food and wine fest it gets pretty crowded on weekends but still not too bad.