From the prospective of somebody that might style themselves a venturesome DIY. I studied and rejected upgrading from 100 to 200 amps. There were several discouraging factors. After my neighbor, the industrial electrician, replaced his box himself, the power company refused to upgrade his service. On their web site, they have a form asking for both what new uses I had or planned and the name of the contractor doing the work. tkrussell has done a number of service calculations here, and I don't think such would justify upgrading my panel, or at the most it would be marginal. I don't remember the lights dimming the way they used to, and concluded I could do without the expense of the 200 amp upgrade even if the electric company would do it.
I am putting the final touches on adding a generator back feed breaker, inlet plug, and interlock, see
https://www.askmehelpdesk.com/electr...se-123290.html I also added a whole house surge protector. To make room for everything, I added a sub panel. Before which, I carefully studied my service and usage. Another factor in not upgrading was calculating how much of my current 100 amp service I can run at once on my 30 amp generator. One thing I like about the interlock is being able to run any circuit on the generator.
I can't eyeball my service wiring and give the likely size or read any labels. Measuring it, I come up with #4 aluminum from the pole, and #0 copper from the meter to the breaker. The meter is a GE CL 200. It is only 10-15 years old, the rest dates from 1970.
The house is about 1900 sqft, gas furnace, dryer, and hot water heater. The A/C is 25 amps at 240 volts, and the range is 10.9 KW on a 40 amp breaker*. Also a 5 amps at 240 volts pump. I have already reduced the load by switching to CFL's. I figure as we replace older appliances, the newer ones will be more efficient. If we really need to, we could replace the electric range with gas.
Bottom line, I don't think we need 200 amps, but if we did, I am afraid DIY stops at the main breaker.
*If the range is 10.9 KW on a 40 amp breaker, might it pop if we had all 4 burners on high and the oven on at once?