Add the laser walls from the tutorial into some maps. maybe on a map they turn on and off at random times forcing players to use portals to navigate the map. idk some cool puzzle like map features that drive portal play and unique maps scenarios, some other things to add to a map could be:

-portal walls that disable and re-enable at certain times

-Mirrors that allow players to reflect their portal beams and create portals around corners using them

-Floors that electrify that drive players to navigate using portals

idk maybe there are some other cool puzzle mechanics that could make interesting maps