Lower Merion is right across the river from the Schuylkill River Trail. The SRT is a mostly paved, mostly flat MUP that runs from Center City Philadelphia to Valley Forge Park and beyond. Depending on where you are in Merion you can cross the river at Green Lane into Manayunk or Fayette Street into Conshohocken.

If you want to stay on the surface streets you will find yourself in suburbia. You can search for rides at a website like mapmyride.com or the bicycling magazine website.

The Bicycle Club of Philadelphia has a library of rides, too.