Is there a reason you want the bar raised vs a counter height bar? I had originally wanted EXACTLY what you describe-ponywall and builtup bar height seating. However, we considered COST as a major factor and it wasn't worth it to us--we wanted seating. Someone can sit counter height just as easily(in fact, I find it much easier to sit counter height than bar height)as at bar height.
Is the 12 inches not adequate to put small counter height stools underneath for seating? (I ask this somewhat selfishly as our new plan has a 12 inch out from the cabinets for counter height seating-I'm just hoping this isn't a big mistake. Should we go 14?)
Also, can you take a picture of the space? If we went bar height, it would be REALLY close to the ceiling for taller people and it would block the view of people in the other rooms. We actually have a wet bar, so not having the bar height wasn't a big deal since we already have it elsewhere. Just curious as to why you'd want to incur an added expense if the sole purpose is seating which you can get just by extending a countertop.
As for the original question, though, I'd build a ponywall, keep the counterspace, build in the outlets into the side as stated for full functionality IF the space allows the additional space for a wall without overly intruding into another space. This was yet another reason we couldn't do it. The added width intruded into a space that you see immediately on entry from our front door.

I have a few reasons for wanting the raised bar. We do not have a desk area downstairs and so my laptop spends most of its time on the kitchen counter only about 10" from the sink. I know that it is only a matter of time before water gets spilled on the countertop and ends up ruining my laptop (although this could almost as easily end up happening on the raised bar as well). It also might discourage the use of the kitchen counter as a dumping ground for everyone's junk as they enter the house from the garage. :-)

I'm attaching a picture of the kitchen as it exists now as you requested.

In answer to your question, in my opinion, 12" is plenty of clearance under the countertop for stools. The 18" comment was referring to the space of the raised countertop.

Here is ours. We love it because it fits our needs for the same reason as the previous poster said. The bar top is 18" deep. It is 42" from the floor, with a 6" kneewall. Our bar stools are 30" seat to floor.

Here is ours. We love it because it fits our needs for the same reason as the previous poster said. The bar top is 18" deep. It is 42" from the floor, with a 6" kneewall. Our bar stools are 30" seat to floor.

{{!gwi}}

We ripped out our pony wall and bar and are replacing it with a counter height peninsula. The raised bar made no sense because our dining room table was three feet away. I think they put it in because an eat-in bar sounded good, but our house is too small for more than one dining space. Bar stools and a table don't look good crowded together.

I saw a good idea on Houzz. They turned the blind corner of the peninsula into a desk area with a stool. Unfortunately, I haven't been able to find the photo since. You could do shelving and cabinets along the rest of the peninsula.

So can you take a pic of the area the ponywall and counter will be "intruding" into?
Here is a pic of my area-we have cousin kitchens;-) (We have since pulled out the upper cabinets, but you get the idea)

For MY space, we were intruding into the window(which we are going to shift over and make a door to go out to our patio, so we aren't TOO concerned about it being near the window as we know it isn't permanent) BUT, this is the view as you walk in the house, so we didn't want additional wall, etc jutting out from the kitchen. If you don't have an issue like this, it would probably be fine.
If your issue is really people putting stuff on the kitchen counter, they will just put it on the bar instead. A cheaper solution is to find some sort of organizer for the existing space to keep stuff out of the way or threaten people with their lives and a sharp knife if they put junk on your counter;-)
If space allows on the far right where the countertop ends, I think an addition along that wall(assuming there is a wall there??) would be to add on some type of desk area-so kind of wrapping the countertop bar. Again, I have no idea what is out of the picture, so this may not be an option.

We have a counter-height peninsula with seating about three feet from the sink. Our peninsula is close to the size of yours. I'm focused on keeping my laptop elevated on it in case of spills, rather than elevating the whole thing. Just a thought. For us, we have a lot more options for using the countertop with the single surface-- it can all be food prep, it can all be an art project, etc.