Erbium and erbium/ytterbium co-doped silicate glass waveguide lasers have been fabricated by silver ion-exchange and their characteristics analyzed. We report on measurements and comparisons made in the lasing properties of these devices, including thresholds, slope-efficiencies and pump tuning ranges. The results presented show that through proper choice of host glass, it is possible to make low-threshold lasers both in singly and co-doped devices.