The house is 4600 sq. ft, has 2 HVAC units, a pool pump that runs most of the time and the following kitchen appliances: gas cooktop, electric oven, 240 volt advantium oven (e.g. in lieu of microwave), 2 dishwashers, wine refrigerator, refrigerator, washer, dryer (high efficiency). We also have a treadmill that will run 30-45 minutes at a time (ideally everyday, but we all know how that goes). We are a family of five (three young children right now), and have a typical array of small electrics. We will probably add a larger screen LCD TV, though it may be plasma.

Does this sound like a load that existing 200 amp service can handle, or would an upgrade be necessary? Advisable in light of maturing children whose electronic appetites will doubtlessly increase? Either way is it a close call, or pretty clear answer?

Remember, electronics do not draw very much contrary to popular belief. So a new TV and an Xbox will not push your usage over the edge. A pool running constantly, a spa, electric heat, motors, an electric dryer, lots of incandescent lighting, etc, are all the type of things that will increase your usage noticeably.

If you are now doing a major renovation, and considering the large size of your home, I'd say this is a good time to seriously consider an upgrade to 320/400 amps.

Rather than us guessing, why don't you take an inventory of the major appliances, along with their wattage and voltage rating (120/240). The wattage will be on a plate. If you can't find it or it's not easily accessible, Google it.

Major appliances would be those things that use electricity to heat or run a large motor. Stove, water heaters, pool motors, spas, clothes dryers, electric heaters, air conditioners etc. are all in this category.

Doing the math would take a few hours and is certainly cheaper than a new service.

A better way to do this is just to hire someone with an amp-clamp to measure the current on each leg of the main with a representative number of appliances working at the same time. A more valid test would be to record use over a day or two with a meter that records and charts the data (fluke 289, for example. Just getting the peaks will be deceptive because of motor start-ups). You want to be less than 80% of your breaker rating.

If you are close, you should consider ways of reducing energy use - it could be a lot cheaper than a new panel.
If you have a lot of incandescent lights, replace the bulbs with energy saving florescent bulbs, for example. Consider high efficiency AC units too. You might even consider changing your water heaters to gas (perhaps gas tankless), since it's available.

A demand load calculation is the only true way to tell. That said, and after doing a few of them myself, I still think an upgrade to 320/400 would be in his best interest.
Reducing consumption is all well and good, but the OP says this is in the context of a "major renovation" of a 4600 sq/ft house.

The point is that we are guessing and doing some math gets you a lot closer. Putting a meter on it and testing it with a reasonable combination of loads gets us even closer.

Reducing consumption is potentially cheaper in the short run, and it obviously can be less expensive in the long run too.

On the other hand, if money isn't an issue - then go for it. (But why ask about it on an electrical forum)