The neighbourhood, from above
I hadn't realised from the map view, but their pushpin is slightly off. 1250 Walker Avenue is east and around the bend in the road from where they think it is: it's the large black-roofed apartment block. If you zoom in, you can just see the blue water of the swimming pool.
The trail running north to south alongside the apartments is the Iron Horse Trail, which here runs alongside a large concrete drainage channel. The trail runs north towards Concord; south towards Alamo.
The large building and parking lot to the south-east of the apartments is Safeway. Out towards the east is downtown Walnut Creek; you can see cars parked on the upper deck of the parking structure on South Broadway.
To the north-east, the large square complex with the trees in the middle is the Castlewood Apartments: nice, but expensive and no vacancies when we were apartment-hunting. Below it, the strip of brown-roofed buildings on Lincoln Avenue are the Lincoln Terrace apartments: we viewed an apartment here, but were lukewarm about it.
East on Lincoln Avenue, on the corner with North Broadway and just south of Civic Park's sports fields, is Walnut Creek Library: about 5 minutes walk from our apartment.
10 minutes to the west of the apartment, out along Walker Avenue and then on Walnut Boulevard, is Howe Homestead Park. This is the starting point for my hikes into Shell Ridge Open Space, which opens out to the west. In the satellite photos it's brown, but right now everything is still lush and green.