I have a very similar setup in my master bath minus the tower. Ours has a drop down in the middle. It is the perfect height for a vanity stool and I also sit to apply makeup. If it were level you would need a higher chair / stool.

Can you share pictures?

Having the lower height makeup area is infinitely more functional. I have never seen a makeup "bar" with the same height as the bathroom sink portion.

When I remodeled I went from the standard two sink vanity to one sink plus a lower makeup area. My power room doesn't have a makeup area but for aesthetics the sink portion of the vanity is higher than the two "cabinets" on either side.

I can post pictures if you are interested but neither of my bathrooms have the same configuration as you will have - i.e. two sinks PLUS a makeup area.

I was trying to figure out the same thing when we recently remodeled our master bathroom. I liked the idea of a continuous height counter so that the mirrors would line up, but I worried that a high counter and mirror would prevent me from sitting to do makeup. A simple makeup mirror on the counter works great for me, plus I need the magnification anyway!

Pics on Houzz

I would want level so that when you're wiping the counter, you can do it all in one big swipe. (Seems trivial, but I wipe my counter down several times a day so it adds up.)

Also, do you need the tall cabinet to the left? I think they make a vanity feel so crowded. Unless it's literally the only closet in your bathroom, I'd go without it.

I would prefer all one level at 36", with a counter-height stool. But I wouldn't have a makeup/hair vanity at all, so I think this is really up to whatever will work best for you!

We kept it level for the expanse of counter top. I just use a vanity top magnifying mirror for makeup. Works fine and looks better IMO.

not done yet, but we went with level for a cleaner look

All one level and use an adjustable stool for the makeup area.

Best arrangement I have ever seen is a separate makeup area in a different part of the bathroom. No shared counter or clutter with the main vanity sinks. I have gotten to use a bathroom set up like this a few times and it is fabulous.

If you don’t have space for that then I would lower the makeup area and have it on one end of the run, instead of in between the sinks. Sitting down to do your hair 12” from another person standing up is awkward. I have had 2 bathrooms arranged this way and never used the middle vanity because it’s too close to my husband. I love him, but…

If the makeup vanity is on one end, then you can put a sink’s worth of distance between yourself and the other sink user. Plenty of space to work on your hair and the sinks benefit from longer, uninterrupted counter space.

When adding a sit-down area, I do prefer a lowered countertop. The break defines real estate, you simply need for those to the left and right to honor that ownership or lack thereof. It provides visual interest. I've sometimes used the makeup counter as an opportunity to add natural wood; a wood countertop and wood makeup stool. Changing the countertop material truly defines the space as being separate from the others.

What other posters have mentioned about elbow room is very important.

We are in the middle of construction and doing counter height across 2 sinks and makeup vanity. Height of counter is 36” and I’ll have a small drawer at vanity. What height of makeup chair (floor to seat) did you get?

@kallinger, I'm not at home to measure, but you'll want the gap between the top of the stool and the underside of the counter to be about 10-12 inches.