Trap arm length

I'm putting in a bathroom vanity sink.
The rough drain is coming out of the side of the wall. The cabinet is 60" and the sink is offset a little, so the middle of the sink is about 36" from the wall where the 2" rough drain comes out.
My question is: Should I extend this 2"-pipe a foot or so before going to the trap arm or should I make the trap arm really long?

If I do extend it should I just glue union fitting or is there another way that's better?

Trap Arm

The trap arm is that distance from the trap to the vent. Extending the 2" pipe will still be considered a trap arm. You can cement on a coupling. You only need to be 1 1/2" so you might want to use a 2 x 1 1/2" coupling. You will also need to add some support by the bowl. Strange that a 2" pipe was roughed out.

Is there an advantage to having the trap arm (and trap) 1 1/2 vs. 1 1/4?
The couplings come in a 2" to 1 1/4 or to 1 1/2.
I assume that the tailpiece on the sinks are 1 1/4 and I can use a compression slip fitting that will take it from 1 1/4 to 1 1/2 on the trap and arm.

Seems like a bigger pipe would always be better.

Thanks Terry

I notice the new avatar like on john bridges site. I presume Terry did that and I thank you terry. I agree with the 1 1/2"

Thanks for the avatar

Yes, thanks for changing my avatar.
I'll have to start a new plumbing project so I can keep checking this forum, since I'm almost done w/ my basement bathroom finish.