What the client needs for this are digital files, and it is fairly easy to explain the advantages in my giving them the work in this format - they have a better idea of what the final result will look like and also save on the scanning cost. Now they get a file that I've worked on, cropping, digitally spotting, adjusting colour balance and contrast to my satisfaction, giving me a greater control over the work. Of course I can't stop them or the designer messing around with them after they have left me, but if I've done a good job this is less likely. Partly to look professional, using a serious looking SLR with a perspective control lens. The digital camera I used was a relatively cheap consumer model that fits neatly into a fairly small pocket, and perhaps would have seemed too amateur.
Peace of mind is worth the small cost of a film and processing.
Also, I'm fairly sure that the client will ask for some larger display prints for the office wall, and possibly for some larger images for use on the brochure cover. Film is more flexible in this way, although if I need to use it, the first step will be to convert the negative to digital in the scanner. So, for the moment, I still take everything on film. If possible I'll also work with digital as well, and it is sometimes the digital that gets used. Even for work on film, most of it I aim to convert it to digital as soon as possible.