I would say remove the upper cabinets to open it up and not have such a divide between the kitchen and dining. Obviously the pillars have to stay but maybe you could add some pretty pendant lighting from the ceiling between the pillars to draw the eye in. I personally prefer the multi level island visually but one level will give you more space to spread out when your cooking.

Is bi-level island working out for you? Do you find it helpful when working in the kitchen? If yes, keep it; if not, change it to a single-level island to open up the space a bit more.

As for your question about granite... not all granite types are dated. In 2019 it is expected that brown granite will definitely be considered dated. Brown granites are often busy and can darken the place. Also, any type of granite that is too busy will look dated. If you like granite, go with some light and easy on the eye options, like White River, Bianco Antico, or White Ice. These are called white, but have many swirls and patterns characteristic for granite stone. If you want to go dark, Steel Gray is a nice choice.

Definitely lose the upper cabinetry, and ONE height , counter level for the top.

Is the kitchen on a slab or basement/crawl space? I would rather have a sink in the island and a cooktop on the perimeter for many reason but primarily safety and adequate overhead ventilation that is not visually oppressive. What type of ventilation do you have now? Why does the cooktop have to stay in the island if you are getting new counters?

If you have 24" b/w the back of the cooktop/range and the edge of the counter on the seating side, then you're probably OK with seating. If you have less -- increase the depth. Maybe add a row of 12" cabinets under the seating side and then the 15" overhang for the seating (12" + 1" thick door on cabinets + 15" = 28", plenty of safety margin.) BTW...15" of clear leg/knee space is the minimum recommended overhang for counter-height seating.

You should really get a true hood. Once those cabinets come down, you are going to be spreading the FOGSS (fumes, odors, grease, smoke, steam) into your other living spaces more than now. Downdrafts are really useless unless (1) the pot/pan is right next to the fan and (2) the pot/pan is shorter than the top of the fan by several inches. Even then, they're marginal, at best b/c they are trying to fight nature -- the natural rising and spreading of FOGSS. (Downdrafts are also loud!) [I've used a telescoping downdraft and I found it close to useless.]