Akhisar is a small city in Aegean Turkey.
Formerly known as Thyatira, and one of the Seven Churches of Asia, it's now a small market town in Manisa province. All that remains of Thyatira is a small set of ruins known as Tepemezarı, covering one city block.
Akhisar is not a tourist town, and you may be greeted with some incredulity by local children. However the people are friendly, and the architecture and horse-drawn carriages make it feel about a hundred years behind the times, and thus well worth a visit.
Once you've seen Tepemezarı (which isn't that hard, as it's limited to a city block), walk around the town and take a look at the lovely architecture and horse-drawn carriages.
Walk around, and maybe hang out in one of the lovely parks that dot the city.
16 Sk. becomes a broad, pedestrian-only thoroughfare across from Tepemezarı, and has a number of restaurants (including a pizza place and a coffee shop) with a nice atmosphere.
If you're not returning to Izmir (or if you are) you might consider Sardis to the south-east, or Bergama to the northwest.