Let me the first one to vote - welt pockets :) I can never be happy enough about these!

Lining jackets. I tend to accidentally rip linings when I wear lined jackets, and I'm not very good at putting them in, and I don't have much motivation to get better. I use pretty underlinings and seam finishes instead.
Luckily I live in a temperate climate.

I used to fear button holes, until the day I decided to become the best button-hole-maker ever. I practiced on scrap pieces for a long time, developed my own little methods, and now I can place perfect button holes all the way down the front of a long dress that also has buttoned cuffs, with no sweat at all.

I must say I still fear them a bit!

Hi! Some of this may be dependent upon your machine, because I go over the entire rectangle of the button hole twice, with the second repeat overlapping just a bit to the outside of the first row. I also never use the stitch that goes backwards. I turn my fabric around so that I am always sewing forward. Does that make sense? After sewing, I take the time to weave in the ends of the threads into the stitching.  I bought some chisels in different sizes where you press down hard to open up the actual hole. I don't use scissors to open the hole. When planning the placement of the button holes, I fuss for as long as it takes to chalk very thin lines at the exact right places in the exact right dimensions, then I stick to those lines. I sew exactly on the lines.

Fusing interfacing.  Surely the most tedious task ever, but good for a facial with all that steam swirling around your face as you do it.  It's particularly boring when having to do large coat or jacket panels that seem to take forever.

I hate, haaate, HATE having to stop machine-sewing to hand-sew something, whether it's weaving the ends in at a button or a buttonhole, or slip-stitching, or blind-stitching. It just breaks my sewing zen flow or something, and makes even the easiest garment feel like it's taking forever. 

I hate to gather!

Im with you here!

When my seam ripper has to come out my mood rapidly deteriorates! 

Putting interfacing together. Surely the most tedious task ever, but perfect for a facial with all that steam swirling around your face. It's especially tedious when you have to do large coat or jacket panels that seem to take forever.