How can I determine what size main water meter is required?
I (literally) dug up the information on our water meter: Currently we have a 2" Neptune T-10 installed. On their website they offer specifications for their different meters, including charts of pressure drop vs. flow-rate. I used some free software to quickly digitize the plots and stick them together onto one chart showing the pressure drop vs. flow rate for 4 different meter sizes:



So, if I assume (please correct me on these assumptions if they make no sense) that a 10% pressure drop would be noticeable (for us: 3.5psi), then I would hit this drop at 18gpm for a 3/4" meter and at 33gpm for a 1" meter. Given that the shower valve we installed provides 8gpm at 75psi (so probably less at 35psi), that means 2-3 people can take a shower at the same time with a 3/4" meter and more than 4 for a 1" meter.

So, I guess going with a 3/4" meter feels a little tight to me (unless we get a booster pump, of course), but a 1" meter should probably be just fine. I don't think we'd frequently be using more than 15gpm anyway, which would only imply a pressure drop of 1psi over the 2" meter.

Note: I'll leave @virtualxtc's answer as the selected one, since he pointed me in the right direction and summarizes things nicely.