Screw Advice Needed

[Steve Fish]

I would use Kreg HD pocket screws and glue. Made for 1-1/2” material. Two in one face and one on the opposing. I have used them for people who still want PT deck railing with very good results.

[Tom Bender]

An advantage to building a bench with a solid top is the possibility of flattening it later. In your case, be very careful to get it very flat the first time.

For most of it cheap plywood will be fine but the top deserves Baltic Birch.