Buena Vista Trail
The Buena Vista trail is an unusual trail in that it is Y-shaped. The bottom stem starts at Buena Vista Rd. The two branches form a connection between two sections of the Edison Road. You can use the Buena Vista trail as a connector between San Ysidro and Romero trails. From the Edison Road connecting to Romero Trail, there is a tiny side trail to an overlook with some benches that you may or may not be able to find.
Buena Vista Trail starts from Buena Vista Road. Follow the trail to a junction where the trail branches to your left (west) and right (east).
If you take the east branch you'll go uphill again on numerous small switchbacks. At the top you'll emerge at the Edison Road, which you can connect to Romero Trail. At the top of the first climb on this road, where it levels out, there is a small side trail to an overlook with some benches. This makes a nice destination and turn-around spot.
If you take the west branch you will climb up to the Edison Road which you can follow down to the San Ysidro Trail.
If you have access to a navigation app, you can connect San Ysidro and Buena Vista Trails using the Old Pueblo Trail, the Wiman Trail and neighborhood streets, to form a loop back to your car. I'll leave this up to you to figure out, though.
There's no mileage for this trail because it is up to you how long you want to make it. Just to the benches and back is probably about 3 miles.