I have used myself, Dwayne's, and Darkroom. My scanner is limited as is my time. I could make the time but that would cut into my baseball watching times which is usually in the wee hours of the morning (MLB ticket).
Dwayne's has fallen off, the quality went way down recently so I decided to switch.
Darkroom is very good and I choose enhanced scan which works out to $15 a roll, that includes download link, negatives back, and a CD with mini proof sheet. Takes about a week from mailing to downloading of images, cd follows a couple days after downloads. They do an excellent job on everything so far, very clean scans. I highly recommend them.
It's starting to add up though as I shoot a lot of film. So I am starting to rethink things and possibly get another scanner for 135. I bought more chemicals locally, so have enough for about 20 rolls. It really doesn't take any space up to develop, just a small card table really, I keep everything in a plastic tub, and hang the film off of Romex wire in a corner of the basement. I put everything away in the tub after developing. 26 rolls = the cost of a Plustek 8200i scanner. The time is in the scans really, that's where I say, shoot, I'm just sending it to Darkroom.