Looks great, well done. I like blue too instead of the common green. I second the suggestions for wider tracks and bigger pads, even if they are not high current. Tracks and pads less likely to lift with soldering.
But who knows, with rising copper prices, maybe NA fabs will soon charge for copper fill so that they can recover copper from the etchant. 
Pads on plated THT pads don’t lift.
And in general, most often digital PCB’s, narrower tracks (above a GND plane) are better because of reduced capacitance. But for a low speed design that also has havy parts such as this big relay, I agree with using wider tracks for more mechanical reliability. With those thin tracks, adding teardrops also helps a bit because it reduces high stress points in the copper where cracks due to mechanical loads (bending PCB, vibration) often start.
Seeing the finished PCB, yes, the traces do look narrow. I ordered 2oz copper to be on the safe side.
Blue PCBs or any color other than green has a price premium that I could not justify.
I must say that I am very impressed with the PCB quality from JLPCB. It’s thick, rigid and the coatings are durable.
In retrospect, I’d like to make the next version a lot more compact, and find a smaller footprint relay with similar electrical specs. This PCB went into a Perreaux 6000B amplifier. It was a challenge to fit it. I could have used a much smaller PCB. But hey, I tested it and it works, 100%. DC detection works, time delay works and it’s installed and working in the customer’s amplifier now.
Calculators abound. 10 mil 1 oz carries a full amp. The few projects I have done I try and keep one sided with as big a trace as I can in case someone wants to home etch it.
Thanks for that additional information.
One of my concerns was how well the traces would carry the current for the speaker connections. I tested with the amplifiers full 330 watts per channel, sine wave, into a dummy load and the traces to the relay contacts stayed cool.
If enough customers ask for this modification, I will update the design to be more compact and use wider traces.
But you could have just used wider traces and zones for the same result. Trace width costs nothing (apart from possibly greater part separation). You have plenty of room on this board to expand the traces with the added advantage of possibly better thermal handling. Personally, I would like to make the traces much meatier for this sort of application. Chunkier copper is fine too but not very cost effective if the traces are very thin.
If possible, ,move j9 and j10 right next to the pins and use copper pours.
I wanted to, but I don’t know how to assign those traces to a specific width before running autorouter. So I get what autorouter gives me and then often there’s not much room to increase trace width after the fact without violating the footprint of an adjacent trace or part.