Okay, let's break down what we know about the Venator.
Largest fighter capacity of any Republic/Imperial ship - it even outstrips the Executor in this regard.
The most point-defence guns seen on a Republic/Imperial ship. It was built to decimate droid fighters.
Impressive shields, but hollow and with a big weak point in its armour right along the top.
A smaller number of very big cannons - later models were upgraded with SPHA-T for close-range fire
Had a second bridge dedicated PURELY to providing flight control for fighters.
So what we have here, really, is a fleet carrier that CAN double as a battleship if need-be. Its main win condition is to ensure that its squadrons win the fighter brawl and then overwhelm the enemy. Its secondary win condition is to use its impressive firepower whilst limiting the amount of return fire it has to take, because although it has good shields, its hull is somewhat squishy.
To me, that implies a high SQUADRONS value, and a low ENGINEERING value, coupled with high SHIELDS and low HULL. It also implies a reasonable LONG RANGE attack, but at the expense of short range firepower. Specialised long-range broadsiders and forward arc ships exist for the Republic already in the forms of the Arquitens and CR-90. Therefore, I could see a balanced arc layout, somewhat like the Interdictor.
It would likely have double (or even triple!) offensive retrofit slots, but completely lack a defensive retrofit. What this gives you is, amusingly, the perfect counterpart for the Victory Class, which was also a Republic vessel. The Victory can tank hits the Venator REALLY can't afford to, and has the short-range power to brawl and force the enemy to consider them. The Venator, on the other hand, can support the Victory with fighters and snipe any pesky flankers (I'd love to see a Republic Victory with a defensive retrofit slot).
HOWEVER - people here have rightly pointed out that there are two versions of the Venator. In ROTS, we see a retrofit that does away with the massive hangar doors (presumably for better armour) and really beefs up the broadside guns. I could see this being similar to the "Combat Retrofit" of the Interdictor, in that it is better suited to actual fighting at the price of the gimmicks that help make it unique.
The "Combat Retrofit" Venator would have lower (but still impressive) SQUADRONS but higher (but still poor) ENGINEERING, less offensive retrofits but more weapons slots (possibly a defensive retrofit too). As we ALREADY have a tanky forward firepower ship in the form of the Victory, the Combat Retrofit Venator would instead have an impressive broadside. The end result is a ship that's relatively capable at anything, but not excellent at anything. Every faction needs a jack of all trades, right?
Anywho, that's my thoughts