I use an epilator for my legs and bikini line and I don't find in between days a problem except when I've been slack about it, but even then I can shave instead and it's only a few days before I've grown back enough for the epilator. The bikini line is hideously painful to get started with, but surprisingly comfortable when I'm just keeping it up. I expect shaving off the whole top bit wouldn't be much worse.
However, I don't think it can be used on the labia, it would grab the skin when I tried it, so I still shave there. My shaving tips are: any day you don't need to shave, don't; try using oil (no need for fancy shaving oil, cooking oil is fine); use good products (I like Mach 3 and King Of Shaves original); if you think you're going to be irritated, point a cold shower at your bits after shaving.