I used to think that suppository applicators were a bit precious, to protect delicate fingers. For the last several months, though, I have been using putter-inners with bisacodyl suppositories whenever I can. The ones I use put the suppository tablets about four inches up my can, which is a lot higher than I can get with a finger. These give a few advantages. The main one is that the suppositories up high have more time to work away from the sensitive nerves in the anal area. For me, that means that they are both more comfortable and work more thoroughly. Also, just putting them in by hand usually results in a lot of greasy goo around my anal area when they melt, which is both uncomfortable and messy. There's a lot less of that when I use an inserter. And using an inserter means the tablets are a lot less likely to get expelled before they do their job. If you like fingers you can always follow the inserter with a finger, and you'll probably have a little more time to play, too.
For shopping advice, I get inserters from Amazon, which lists a fair selection as vaginal creme inserters and as rectal suppository inserters - for our purposes, both are the same. I bought about three dozen years ago, and still have most of them, even after occasionally giving them to friends. I suggest the plainer the type the better; for example, ones with threaded ends are likely to be harder to clean, and the business end should not be much larger than the tablet. Most of the inserters come individually wrapped, and are easily cleaned, although they are meant to be disposable; I just use a cotton swab (or balled up tissue) for the end, and rinse them off. The prices at Amazon are around fifty cents to seventy cents, though some go for more than a dollar; they come in packs of around six to sixty.
I would not use a straw for the reasons several posters suggested: the edges can be sharp and injure the rectal wall. Besides, I kind of like the feeling of having the inserter put way inside me.
If any neighbors go in with me on a box of a hundred bisacodyls I always throw in one of my inserters as a surprise. (By the way, neighbors here are more likely to borrow a suppository from each other than a cup of sugar. We don't find anything embarrassing about buying them or using them - or promoting them.)
Now, if you want to know my pet peeve, which is also the pet peeve of everyone I've introduced generic bisacodyl suppositories to, it is how you have to use a blow torch to unwrap them. I think Dulcolax must pay the generic manufacturers to make them like that: it should not be so hard to perforate the tablet strips and make the wrap actually peelable. Instead, we usually have to cut them open awkwardly or use two pliers, one on each tab!