I haven't tried them but Portland has a bunch of street food if your wife and friends are up for it (only thing that comes to mind in the cheap catagory.)
Food Carts Portland
For nice you can do this:
Portland City Grill - Home
I know you said they don't drink but many of the brewpubs have good food and don't mind if you have soft drinks.
I realy like the food here:
Deschutes Brewery & Public House
210 NW 11th Ave
Portland, OR 97209
Neighborhood: Pearl District
(503) 296-4906
And here:
Rogue Ales Public House
1339 NW Flanders St
Portland, OR 97209
Neighborhood: Pearl District
(503) 222-5910
And
(Great Reuben)
Goose Hollow Inn
1927 SW Jefferson Street
Portland, OR 97201
Neighborhoods: Goose Hollow, Southwest Portland
(503) 228-7010