Benchtop bench vise: end or side?

I have mine on the left front corner of my bench (I'm left hand dominant) and can spin it 90* to then have access to it from the short side.

If the vice can be rotated on its base, mount it at a corner so that the material clamped in the vice can extend downward past the front or end of the bench.

If you're only going to have 1 vise, I'd put it on the side on one corner. I'm right handed so I have a vise on each right hand corner.

Unlike Don, if I had only 1 vise it'd be on the end of the bench. The reasoning is that you can't easily hold a board for planing on a side-mounted vise (at least not one that's very long), but you can hold a board upright in an end vise for cutting dovetails. But there are a lot of different ways to work and hold wood. I've always found it surprising that Paul Sellers (on youtube) works without an end vise and without benchdogs (with only a vise on the side).

I think about 2 feet wide (+/-) works pretty well. Length will depend on the type of projects you do. 5-6 feet may be a good starting point for thinking about it.

In an "ideal" world, there would be both. One on the face of your bench toward one end (left if you are right handed, right if your left handed) and one on the end. This arrangement maximizes your ability to hold work in various positions.
There are a lot of choices for which style of vise you add to the face of your bench, each having their reported pros and cons. It's really a matter of what you like and what works for you.

My own personal prejudice is against the shoulder vise. Ain't having one of those things in the shop. If one DID manage to creep in, it would only stay in place long enough for me to get out the Sawzall. But that's just my own personal hang up……

Plus one on the 24" +/- This is a very comfortable and convenient size for most woodworking.

I'm in favour of the end vise and I would go with 24 - 30" in length. I don't use mine much for dovetailing but it's used regularly for planing smaller components.

Do you have an example of what kind of benchtop bench you are talking about? I have seen a lot of various sizes and styles. Knowing what you have in mind may help.

Interesting question. The first bench I worked on had the vise on the left front corner. I have built several through the years, and changed things, but never my vises position. Interesting reading about what others think on this. On the size question I do know each bench I make is smaller than the last one. Now about to make another, and I'm thinking 4' wide, 2' across, and about the same height as my TS, which is 36 something, but I'd have to measure to be sure on the fraction.

I've taken to making all benches, and tables the height of the tool nearest to it, just wonderful to have same height support.

But most importantly your bench, your rules. Make it comfortable. I think size is a relationship with what you make.

I have bench top bench that has a Moxon style vise on one side and it also has a small face vise on the opposite side. It's easy to turn it around so I have a choice of which vise to use.

I won't say end or face. What I will suggest you consider is how heavy/stable your bench is.

Will it move/rock when you push/plane/saw across the short direction of the bench? Of course if it rocks when sawing, you're doing it wrong anyway, but a light weight bench can easily be rocked when planing across the short direction. This can be quite frustrating, or at least very annoying.

Keep in mind too, I know nothing.