Llandegla is a great Trail Centre. A full afternoon can be spent in the area.
Marin I love. Old school XC, some really nice single track and lots of fire road climbs.
Penmachno, not everyone’s cup of tea but some nice single track.
As Jekkyl says look on the flat tyres routes
Lots of easy to follow routes.
For me a day exploring the Clwydian mountains and a trip in the afternoon to Llandegla.
Day 2 follow one of the above route guides