Looking to get into a bigger boat that can handle more speed and rough water. Have been looking at ATs for awhile and love the design and quality of them. HOWEVER, I am interested in staggered engine setups only and it seems that ATs never offered it in any of their boats.

Just one in a 37 with 600hp and Bravos.
Ask Pat about it. I'm sure you will get an ear full.
You don't need that kind of "what ever" with any AT!!!
ATs are synonymous with speed and BIG WATER!!

NOT trying to talk you out of it, but what has you convinced you want a staggered setup?

'Tis true, most of the boats have been side/side setups, but there are a couple out there with different setups like staggers and triples.

Right now the current 37' ATs are running 86-90mph with traditional transom mounted XRs behind 525EFIs. This is VERY VERY competitive, (if not exceeding), what the other manufacturers are doing; ESPECIALLY CONSIDERING your cabin looks like below with AC, Fridge, Microwave, Enclosed Stand-Up Head/Shower, Corian countertops, and a host of other cabin creature comforts that other manufacturers don't even offer.

Heck, ActiveShack's new 37AT turned 87mph with all of the above AND A GENERATOR.

BTW, the 43AT is going to have lots of engine configuration options; potentially staggered.

I do lot of my own work and would love staggered engine setup just for the fact of getting things done easier the a aside by side setup.

The only thing that gets tight is getting the inner two rear most spark plugs. Most of the newer stock Mercury motors are 100 hours between plug changes. Rich (Docmanrich37) changed the plugs a LOT on his 37AT after he did the Whipple install, and he could do a full set (16) in less than an hour. Worst case is pulling an engine. James (excursion) has a nice overhead chain hoist in his shop, and can have one of his engines swinging overhead in about 35 minutes; from a 100% dead start.

There is a LOT of room in front of the engines on a side/side 37AT. Plenty of room for sea-strainers built into the floor, and pull your water pumps/impellers right off the front. Fuel/water separators and filters are right in the front of the engine compartment as well. All of the Mercury motors for the past couple years have had oil pan drain tubes for oil changes, so there is no issue there.

I do all of my own work as well, less something that falls under warranty. There is plenty of room to work in the engine compartment of the 37AT.

doesn't stagger give a better cog, and since the drives are lower, they stay hooked up better?
Every raceboat is staggered.
Only reason i could not see it being better is if the hull is not designed for it, and is designed for all the weight in the stern.
Loss of cockpit space is not a bad thing if you don't need it or don't care.

What is the true advantage of being stagard? Balancing the weight for faster speed?? is that it? anything else?

Drives are on a 18 inch instead of 36 in centerline. less drag from drives. Much harder around docks. It is not very practial in a pleasure boat, however Cig and Donzi do make staggered 39 and 38 footers.