I am building a home (could eventually be 8000 sf+) and doing most of the
Electrical work myself, but I am working with a electrician not
Familiar with my issue. I have around 200 circuits so far, which I
Know is much more than usual. I have limited the # of receptacles per
Circuit to 6, and I have dedicated circuits for 5 microwaves, 3
Refrigerators, many plant ledges with receptacles, 3 heat pumps, 3
Furnaces (1 electric), am going to have concession-like equipment in
The game room (slush puppie, hot cheese), etc. I had planned on 400
Amp service, but it seems I have gone overboard! I have looked at the
NEC, but is there a rule of thumb to calculate the amp service
Required for a total of amps of breakers (certain percentage?) I was
Hoping to have sub-panels behind the main panels, but it looks like I
Will have to have many main panels with a very large amp service?

There is no "rule of thumb" to size a service. The calculations are done according to Article 220 of the National Electric Code. Basically, general lighting load is 3 watts per square foot of livable space, then fiquiring in certain required loads, such as appliance circuits,laundry, and then adding the major applainces, heat, ac. All of these are done with certain demand , or derating percentages.

The distribution method can come later, most likely with several subpanels for the branch circuits.

The quantity and rating of branch circuit ratings is irrlevant.

Your electrican does not know how to size a service? Ask him if he knows how to use the Examples at the back of the code book? How does he normally size services? Guess? Dart board?

If you give me the actual square footage of total finished livable space, list each major appliance, ranges, dryers, hot tub include load in amps or watts if possible, list load amps or watts of each heating and air conditioning, I should be able to get your service sized.