It just depends on what church you are talking about specifically, as churches in both communions can have drastically different lengths. Also, there is no uniform liturgical heritage in the Non-Chalcedonian communion, so a Coptic round of services might be longer than an Armenian one.
My Orthodox parish offers Great Vespers and confession on Saturday evenings which lasts for about 45-50 minutes, and then a full Matins and Divine Liturgy every Sunday. On Sunday mornings, Matins starts at 8:00AM and the Divine Liturgy gets over between 11:30AM-12:00 noon depending on the Sunday. Sometimes it goes even longer if there are extra services tacked on like on Pentecost with kneeling Vespers, which adds another 45 minutes.
So just on a typical Sunday morning services last 3 1/2 to 4 hours.
I visited a local Coptic church once and I think I remember it lasting over 3 hours. I can't vouch for times in the Armenian, Ethiopian or Syriac churches, but also keep in mind that there times probably vary from church to church as well depending on how fully they perform the services.