TravelPortland.com...a good place to start for the best, latest recommendations.
Rose Garden..the international rose test garden in Washington Park is beautiful in the summer. there are lots of other things to see at the park (the japanese garden for example) and it's worth an afternoon walk. there's a shuttle which is walkable from the hotels and a bus.
Shopping... the "Pearl District" neighborhood is where the venue is located. it's your standard modern, fancy shopping/condo/urban neighborhood. lots of shops and some decent galleries to browse. Head west and you'll run into 21st and 23rd avenue. 21st has some nice bars/restaurants and 23rd avenue has lots and lots of shops. you can take a cab, have a long walk or hop on the portland streetcar. there's also a mall downtown called pioneer place which also has some nice shops.
Powell's Books...an overwhelmingly large book store you can spend the entire day in. classically portland.
Ground Kontrol...if you'd rather play pinball and drink.
Forest Park...forest park is one of the largest urban forest reserves in the country. as such it makes for some really great hiking and you don't need to travel very far to get there.
Waterfront and EastBank Esplanade...a nice river walk in the morning or afternoon.
the east side...we live in SE portland and there's lots of stuff to do. same for NE and N portland. Hawthorne, Mississippi and Alberta are all great streets to visit on a summer day. mt. tabor park has great views and nice little trails. if you want to cross the river the 20 bus line runs on burnside. either that or a cab since it's a long walk.
Food...a pod of food carts is close to the hotels at sw alder st. between 9th and 11th. lot's of decent options. also near the hotels is kenny and zuke's which is as close as you are going to get to an east coast deli. urban farmer at the Nines hotel has a nice breakfast if you're in the mood. we enjoy isabel pearl for lunch and brunch and it's right by the armory. to be honest there is all sorts of good food in portland so you can't go wrong.