I opted to have my sub-panel off the new great room - 100a
Main reason is the sub will be my main power distribution for my Christmas display
2nd reason is I have to go thru the basement to get to the garage
The sub is right above the garage & running circuits from either the Main panel or the sub will be very easy
Main reason to access the sub will be if an outside circuit kicks out due to rain/snow around Christmas
It's actually a 200a panel - 40 spaces being fed w/100a
---and I expect to fill most of the breaker spaces
I thought of another small sub in the garage
But at present I do not have any huge need for power out there
If I am using a tool I usually have not had a breaker kick off
And with multiple circuits (5 or more) in the garage I'll be able to split up any loads