Charlotte, NC...
I wanted more space, currently have 150AMP box with not many spaces.
For an extra $15 or so, the contractor could have put in 200 AMP in the first place, but I digress......
Got a couple of estimates for each job (new main panel vs. subpanel), both came in close.
We already had a 200AMP meter, and the wires from the transformer to our hosue were big enough for the 200AMPS.
Just to change the box to 40 space 200 AMPS and the wire between box and meter was going to be about $1500. Pull a permit, cut the power (Duke Energy won't turn power back on till you have inspector's approval, that could be quite the circus).
Subpanel was about $600.
So unless you are planning to be welding with one hand, using a plasma cutter simultaneously in the other, air compressor running all the while, while your wife is drying clothes in an electric dryer and your electirc heat is on in the dead of winter and there's a couple of turkeys cooking in your double electric range.......
I'd suggest the subpanel.