Multnomah, 100 amp, directly next to the panel with a short conduit run. I haven’t spoken to permitters yet. The electricians who didn’t recommend upgrading the service saw no safety or usability issue with the 100 watt panel. And as a practical matter, I’ll charge at night almost exclusively, when everything but the AC and fridge are off.
So I'm not an electrician but son of an engineer and have been doing IT systems integration for almost 20yrs some of that being industrial controls I've been around a good bit of both low voltage data/comm's and medium distribution 120/240. Do you have gas appliances? If you are running electric heat, electric stove, electric water heater, etc then it very well could get dicey with the 100a service, however if you are mostly gas then I'd tend to agree and I wouldn't automatically go for the load center upgrade. HOWEVER, you will probably at some point want to if you are planning on selling the house. I don't know what the permitting office is like in MultCo but they're probably a bit more picky than where I am in unincorporated Washington Co.
how do you feel about your DIY skills? This is probably one of the easier things to do if everything is as you described. Given it will be a single outlet branch circuit at 240v you dont need to worry about a lot of the NEC (electric code) for 120v multi-outlet branch circuits.
Pick up some 6/3 in a slightly longer length than you need.
Get some "black button" nm (non-metallic) cable connectors in the appropriate size for your panel punch outs (mine were 1") I've actually got a box if you wanted some.
Make sure to get a double gang wall box thats at least 30 cubic inches (box size is dependent on conductor size)
Make sure to leave at least 1/4" inch of sheathing on the wire bunch where it enters the panel box and the wall box
Some staples to secure the wire to the stud (must be secured within 8" of exiting the box)
Add a staple every 54" after the first one unless it runs through a stud
Any studs you need to cross drill a hole at least 1.5" from the face of the stud, add nail plates to the stud if you cant get 1.5" away from the face (I added nail plates just to be safe. they're .44 cents at HD).
Make sure to add orange fireblock foam in the holes to any exterior wall or if going through floors.
Make sure you dont have more than 4, 90* bends across the whole run
There's probably some more in there I'm forgetting but if you have any desire to DIY this, hit me up I can provide you the NEC regs and suggestions on where to get the bits here locally.