Last Year for me (April/May):
Spider Wets:
Waterhen Bloa (size 14)
Snipe and Purple (size 16)
And best dry:
JT Olive Dry (size 19)...totally mental fly, looks amazing on the water, easy peezy to tie but make them slim.
IME if you are fishing wet's "across and down" it can be good to put on a weighted fly on point, beadhead March Brown/Endrick Spider or PTN etc so the flies will fish at different depths then "lift" at the end of the drift. Or just mend several times on the drift to let the flies drop down in depth. Effective on windy Don days !
Lindsay