I have a desk job too and need to be at my desk for most of the day. I use tena products but I think you have to shop around a bit to find the right product for you. Alot of places do free samples so you can try out the product first. I wouldn't worry too much about the crinkly noise as most general office noise will mask it, although it can seem horribly loud if you walk into a meeting room and everyone stops talking! I find that sitting at a desk means you can be soaking between your legs and dry elsewhere. If you're a man, making sure your penis is pointing up will help with this and a pad of some sort in the bottom can help a bit with the spread. If your employers not sympathetic to the amount of time you need to change, insert pads can help.
Plastic pants shouldn't be necessary with disposables of course but everyone wants to feel secure! If you're sitting down all day you don't want the leg holes to be really tight. If you can get rubber, these tend to be a bit more forgiving around the legs but do add a bit of bulk as they're thicker and heavier.
Take more care of your crotch area as it will be sitting on a wet diaper for hours at a time.