I was born near Aberaeron and I go back every now and then. When I lived in S Wales my regular route to the coast would be through Lampeter and onto Aberaeron. It's a pretty little town with a nice harbour as pointed out by Clarkson recently. The coast road up to Aberystwyth is lovely with some good sea views and changes of elevation.
The road north of Aberystwyth, A487 through Bow Street is pretty slow going with village speed limits. I did it on the way back to Welshpool on my latest visit to Aberaeron. Never again. I'll use the A44 next time.
I guess for you it will just be half an hour of slow going. Once past Talybont it is better. The route after Machynlleth to Bala and beyond is fine to the A5. No idea after that. I often do the run to Bala and back down to Machynlleth. Great scenery. You are in the Mach Loop so on weekdays, might get some aerial entertainment from RAF Valley. I'm usually heading to my favourite chippie in Aberdyfi.