I always use 45º angles but I think they only worth (in audio applications) for self etched boards (without solder mask to protect them from lifting) But I also like more the design like that, 90º seems too old school for me
In many cases the center tap is very useful, if you are working in the same project with tubes that only have 6.3V heaters you end using 6.3V for everyone, so you short the ends together (4 and 5 in the 12AU7) and apply the 6.3 between there and pin 9.
The star distribution of B+ isn't optimal at all, you should take the trace from the input to the caps and from there to the tubes, same thing for the ground of the PS, to the caps, then to the tube. (of course when I say tube is the anode and cathode resistors respectively if there are any)
Then the signal ground goes from the input transformer, to the first tube, to the second tube, to the output, following the path. Here is where it gets tricky since you also have to connect the caps and PS ground, just connect the PS caps close to the tubes and then use the cap on the output tube to go to the PS GND. In any case, in tubes circuit current is pretty low, so you can take some more freedoms than working on SS circuits, but it's always good practice to optimize this things.
As Ian said, place your first tube close to the I/P transformer, the other tube close so heaters run short traces. Then the GND from input to output, at the output tube you make a split going to PS GND. Place the caps close to each tube, add the PS rails. Route everything else as tidy as you can. The GND traces at the input are particularly strange, that cap at the lower left corner runs a trace all the way just for it, you should probably move that cap, it makes the GND make that huge loop from top to bottom.
I draw my boards quite a few times before I'm happy with them, don't worry, keep routing! Good luck with that!
JS