The real attractions in this corner of Oklahoma sit outside town. Two natural sights in particular justify a visit to Alva.
The Salt Plains National Wildlife Refuge, about 40 miles southeast, is unlike anywhere else in the state. You can dig for hourglass selenite crystals on the salt flats (April through mid-October), watch sandhill and whooping cranes on migration, and drive through a landscape that looks more like a salt desert than the landlocked plains you might expect. Give it a half day at minimum.
Alabaster Caverns State Park, about 30 miles south near Freedom, contains one of the largest natural gypsum caves open to the public in the world. Guided tours run hourly and last about 45 minutes; the cave stays at 50°F year-round. A bonus in summer is the bat emergence at dusk.